Welcome.
Here is another thread of helpful links.
FWIW I totally advocate for putting off 5* heroes initially, having made that mistake myself. I got my first 5* at 2 months and proceeded to start working on him immediately. It took me over 8 months to finally max him. Meanwhile, I could have maxed 4 4* or probably a dozen 3* instead. Needless to say, focusing on the 5* cost me months of progress.
Getting a set of maxed 3* heroes makes it easier to get a set of maxed 4*, which in turn makes it easier to get the 5* maxed. It’s all about patience, even if you are a spender to accelerate the progress.