When she was a baby I always waited till she was asleep (which was nearly NEVER) or when DH were there.

NOW neither of us can shower without DD stripping her shoes and socks (not as handy in stripping down completely yet) and getting in uninvited So we just give in and put her in the shower with us/DH. I just place the bathmat on the showerfloor, give her a bucket and a cup and she will sit there till New Year's. She will even come and get me off the sofa and get into the shower and tells me "mommy shower" Darling angel!

Needless to say, we shower at night when she is sleeping .. I just bring the monitor in the bathroom with me, just in case she wakes up.