Might depend on a few things, if you want to breastfeed and how long (you might have to pump at work etc.) and what your childcare arrangement may end up being. They do tend to get sick a lot when they start daycare and you can be constantly taking time off for that.
I went back 2 days when ds was 13. months but only because he could stay with my mum. a year later he started 2 days daycare and later we upped to 3 days but it was a tough year as he just kept getting sick from daycare. So lots of time off work. I love part time work, 2/3 days a week is perfect for me.
Ds is almost 3 and another on the way, I've no plans to return to full time work for a long time down the track.