It will take a while to build up the muscle.
When it comes to training the PC muscle I disagree with the majority of people here it seems.
The advice you will generally get is to go for the burn. Initially this will happen quite quickly but as your muscle develops you will find that you can do more and more before you reach the burn.
By burn I mean when the muscles start to build up lactic acid through anaerobic operation. If you have run or jogged or trained you should know this feeling.
Personally I think in yoga terms :) So for me building up the muscle is not about the repetitions done but controlling and holding the muscle, to build strength as opposed to bulk.
Either way you should probably mix in some longer holds (5 seconds or more).
Don’t worry about not being able to kegel much yet, it will take time to train the muscle.