are there any exercises i could do while i take a hot shower?
Sure, you can do the newbie routine, but it depends on your experience. Try these stretches (left,right,up,down), some JAIS, and if you have more time, do some jelqs.
BPEL 7.00 in (17.7cm) WANT 8 in (20cm)
should i use any sort of rep count or time?
Read my routine thread (link in my sig).
Early on, I did virtually my whole routine in the shower.
The warm ups are the best.
I take a wash cloth and get it hot with the water. First I take it and wrap it around both my ball and dick. By keeping my knees together I am chunky enough so I can tuck the corners next to my pubic pad and it stays. I look like a jungle indian right out of National Geographics. Do this 2 or 3 times and your bag will hang like a billy goat.
Then I just wrap my dick real tight with the wash cloth for about 5 mins. Making sure to reheat the cloth on occassion. Make sure you warp it tight enough so that it will stay on you dick by itself. This leaves your hands free to wash the rest of you. Then when you get out of the shower your dick is really receptive to PEing.
Doing PE in the shower dries my skin, but warming its fine for me.