I started playing a week ago, and have the same concern. I bought these little rubber finger tip things - Gorilla Tips. So for each practice, I play without them until I would want to stop for the day due to pain, then I put the finger tips on (left hand, fingers 1,2,3, not pinkie since not using it as much), and then I can play for a while longer - indefinitely, really. It might take me longer to develop good callouses, but they'll come eventually, and this way I can practice longer. I'd like some feedback on this idea ... Any thoughts??

4/14/20 - Just to follow up on my note above...

I've been playing for a month now, and my callouses have developed such that I no longer need the rubber finger tips! ( So don't buy 3 sets like I did! You won't need them that long!)