I have been showering with our boy (now 8 weeks old) since he was 5 weeks. I hold him firmly in one arm around his legs under his bum, against my chest and use my other hand to lather him with his baby bath stuff. He likes to have his head in the water but if he didn't like it I would never force the issue. Before and after the shower I rest him in a towel in our portable baby bath as he is safe and secure in there while I get undressed/dressed etc.. good luck and I hope you shower experiences are joyful and fun!!
The ages of my other miracles first shower:
Miss 8 - 11wks old
Miss 2 - 9 wks old
Kel,nsw, Girl '97 & Girl '02 & Boy '05