Normally if you hear someone doing a 10week cylce its with TestProp because it works faster so you get more out of a shorter cycle.
Honestly if it's your first cyle if its only going to delay you a bit id wait and get the extr vial or start and you have 10 weeks to get another one lol Then you can extend it if you want or you feel you want to stop at 10 you can do that also. At least with your first if you run 12 you'll know if you want to go that long again or you can make that judgement call from there on out
