I’m going to be starting the week’s wait for SH20 later today when I get a builder free. I’ve been playing 101 days, so it should be done on day 108.
My alliance leader calls me a leveling maniac; it will be pretty hard to beat my time by much, @Enigma-MT, so two months looks more likely than one month. (Assuming you have VIP with two builders; far longer without it)
I’ve used a build plan which is ~97% laser-focused on getting TC20 ASAP. (My only builds that aren’t working directly toward that are a Barracks-3, and my forges are at 5 (under the barracks), 16 (for dragon attacks in events), and 8 (so I can craft anything up to axes when my big forge is busy or upgrading)
Iron storage is generally at the minimum needed for a SH upgrade. I store my food in TC13, so I just need to upgrade food storage for the minimum needed to do WT upgrades, forge, and training center research, and houses need to hold 72 (with TC13), and 102 (with TC20), and are much more convenient if they hold all the recruits I can haul in on a farming run of all my flags; 86 right now which generally covers it.
I’ve considered upgrading my low forge to 10 for mana potions and my big forge to 17 (timestops) or 18 (tornados), but that is going to be after TC20…
I also would have gotten there a tiny bit faster if I had slowed down upgrading my mines and farms and watchtower, but those are a long-term investment, even if they might have lost me a few days, even a week along the way. (WT is 17, Farms are all 16 except for one still at 15; Mines were going to be all 18, but I had a couple times where I had a free builder and not enough iron for my next project, they now are 18, 18, 19, 18->19) My TCs are 18->19, 13, and 11, according to my plan.
I started out with my mines and farms maxed to my stronghold level for max production. I was fighting food shortages for a long time. But at about your level I started getting serious food surpluses. Right now I’ve got 10M accessible food banked in TC13 (87 days), and a bunch more (but not accessible) banked in TC11 (69 days). You could probably safely stop upgrading farms at level 13 or 14, or whenever your food shortages seem to be a thing of the past even if you have several heroes to ascend all at once.
That said, they will be needed eventually. And once I get TC19 researched (there goes 1M food!) I’ll be having a minor rugged clothes burning party and make myself somewhere between 200 and 1000 1* feeders all in one day, before I get to TC20 
So I don’t really regret my surplus, or getting my farms ahead of myself. It would have been more of a waste if I’d not had TC13 to bank it in, and been happy to get a the remaining 3* heroes I want (but mostly feeders) and a few more 4* heroes I’m happy to use–My first TC13 pull was Boldtusk!
One big advantage of delaying optional upgrades is that your iron production increases as you level up, especially the 33% bump when you get your 4th mine at SH15 up to match your other mines. The bump up leveling all your mines is modest in comparison, 3-5% per level, less at higher levels. Since you make iron faster, spending a lot of iron (storage buildings are particularly expensive) later when you are accruing it faster will save you time in the long run.
I worked this out for some members of my alliance and thought I’d share it here; it might help you too.
Full Build plan for TC20 (long, lots of gory details)
Training Center development schedule on the way to TC20:
- Get one training center “Alpha” to 11. You won’t ever need to upgrade this one again. Use it as your “Recruit Bank”. When you farm, store away recruits in it, and build the surplus up to at least a week, and try to keep it there. (More isn’t a problem; mine is ~70 days right now)
- Use TC “Baker” for swords and backpacks (TC1 & TC2), if you have enough to keep it running either while you are playing, or while you are away from the game. When you are out, switch it over to TC11 (if it is high enough level) or TC4 if it isn’t.
- Get your third, “Charlie” to 13, and use it as your “Food Bank”. It will also spit out 3* heroes every two days, with the occasional (3~5% chance) 4* for your roster. If you have surplus food, you can remove recruits from the recruit bank, and add them to the food bank; do the reverse when you need more food. (If you aren’t building up a food surplus, upgrade your farms….)
Training center development phase 2: (Stronghold 14~19)
- Take TC Baker (sword/backpacks) offline and upgrade it, catching up or keeping up with your stronghold. When it isn’t busy, run swords or backpacks as usual. (If you only have a little time between upgrades, you can run swords thru faster at a higher food cost with TC3.)
- Get your food storage upgraded so you can research TC19 and then TC20. Two at level 13 and one at level 12 is the minimum.
- With TC19 researched, if you have a good amount of food and recruits banked, you can burn through some rugged clothes you’ve been accumulating so far and make a ton of 1* feeders. (Make sure you have enough food to feed them to heroes if you make a big batch!) This can give your heroes a sudden growth spurt.
Training center development phase 3: Stronghold 20 achieved
- Build your last TC, “Delta” and upgrade it to 4 immediately. It will now switch between TC1/3, TC2, and TC4 when you have swords, backpacks, or are out….
- When you’ve run as much TC19 as you need for a while, upgrade TC Baker to 20
- Meanwhile, upgrade food storage so you can research TC20; Minimum is the new one @9 plus 12 and 2x13 that you needed to research TC19
- Next, or while you are researching TC20, upgrade your houses to hold at least 102 recruits, if it isn’t at that level already. (142 total should make the transfer a bit less tedious)
- When you have TC20 built and researched, move your food bank from TC13 Charlie to TC20 Baker. You’ll have to leave the one currently in progress to finish. You will have to move some into TC11 Alpha since 20 takes more food than 13. (TC20 makes a better food bank than TC13. It stores a bit more food, and more importantly, it generates far better heroes: ~75% 3*, ~20% 4*, ~5% 5*
- When TC13 Charlie puts out its last 3* feeder hero, upgrade it to 19.
- Upgrade TC4 Delta to 11
- At this point, you can upgrade Charlie and Delta to 20 as needed, along with upgrading other buildings.
SH20 looking for heroes: You will want to run Alpha at TC11, and could run all three others at TC20, until you pull a hero you want to level up. Then switch over to….
SH20 building heroes: You will still want to run Alpha at TC11, Baker at TC20, but the others will be making feeders, at some combination of TC1/3, TC2, and TC19 as you have the food and swords, backpacks, and rugged clothes available….and when you don’t, fall back to TC11.