Depends on the crèche. I know one where the carer is an old colleague of mine, qualified and with years of experience.

I know another where the main carer is my sister who is, at best, a space cadet. I wouldn't be in a hurry to do it.

I second walking. I also had a bike trainer, I could put baby down next to me and smash out a few ks while she plaed. Keep a skipping rope near your clothesline (or somewhere) and do 2 minutes every time you see it.