Pete, how much you should practice per day is an individual decision. Lot's of people are time limited due to career, family requirements, etc. and have the decision made for them. Others, such as me due to retirment, and obviously you, aren't so restrained.

I think it is a fairly well accepted fact that the more you practice the faster you will progress.

But there is a point of diminishing return. One can only absorb so much. Also, you don't want to impose upon yourself a negative thought with practice, especially with something like finger tips hurting. And practice sometimes, you will find, is just frustrating. If the fingertips hurt back off for a bit until they quiet down. Build up the callouses. If you get frustrqted back off and play something fun!

If you can practice a couple hours a day a lot of people around here are probably going to be envious. Do that for a while and see how you do. I hope some of the instructors on here will share their thoughts.

Good luck to you.