Yeah it can definitely take a lot longer than 2 3 months to get a decent team together, even if you buy a lot.
For new players who are willing to spend, if you don’t have it already, I recommend investing in VIP. Having 2 builders is a great boost early on, will make it easier to get your training camps up to level 20 quicker so that you can start collecting more heroes for your war roster. They’re just vanilla heroes so not as good as some of what you can get from summon portals, but season one 4* heroes are more than good enough for completing a lot of the game content.
… and before anyone tries to say “what does that have to do with ascension materials? stay on topic, man” … it’s important to have good heroes because they can make it easier to get ascension materials. It can be a bit of a Catch-22… you need ascension materials to level your heroes, but you need leveled heroes to complete many of the quests to get the ascension materials… it’s okay though, you’ll get there eventually. Easier if you focus on the 4* heroes first, the 5* heroes take a lot more time and resources to ascend.
Again… 2 3 months is still very early for this game. Takes most players a year or more to build up a really solid fully leveled team. So no worries.