From the start! It's a great time to enjoy with your little bubs if you feel comfortable. We put Charlie in the shower very early on so that he got used to it...it was often his only time with Dad before bed as DH was gone before he woke up & home just before bed time. Just keep it nice & warm & not too fast & they should enjoy it - though they are slippery little suckers LOL. As for bath, even better as you can just cuddle with great skin to skin contact and sit back & relax. If you are comfortable with it...go for it!!