When my DD first started I would stay 20 or so mins in the morning, breastfeed her and then go back at lunchtime and spend my lunchtime there (breastfeed again) and then go back and pick her up a few hours later. All in all she was never there for more than 4 hours without seeing me.

I think it did her transition wonders. I kept it up for about 5 months until she dropped the lunchtime feed and I started using the time to go to the gym! They never complained about me being there at all. I never helped her go to sleep there though - just because she slept in between the times I was there. Instead I introduced a piece of muslin which I slept with and that helped her a lot.