My DD at 14 months hasn't had any more than 3 hours away from either myself or DH. But saying that if i had close friends or family that lived nearby i would offload her in a second..lol
I think it is an individual choice, you can only decide when you feel comfortable about it, maybe work yourself up by leaving her with family that you trust while you do shopping to start with etc.
Mind you once you have two kids i would think that it would be good for each child to have the chance to have one-on-one time with each parent once in a while..