How many jumps is dependent on whether or not you have the rested buff, considering the XP boost the buff gives you.

How long it takes is dependent on your amount of activity in the game. I honestly found my jump skill increasing faster while building elaborate things versus exploring simply because I hit the jump button more while building.

But I suppose if you just stood in one spot and spammed the spacebar...accounting for stamina loss and downtime, I reckon it would take days (real-time) to get to 100.

Also, yeah...your vertical leap is easily 2-3 meters at 100....