It is more usual to modify time before and after an event to say "long before that time" or "long after that time". Then we can use "much" when modifying those phrases: "much longer before that event". I hope that helps :)

I beg you, *please* use "long" here.

"Alot" would be perfect as for me

I just noticed that if you are modifying the learning and not the time, then of course you can say "learnt much" or learnt a lot"

It should be much.