I don't know for certain, but I'd guess at least 24, maybe even 48 hours or more. I should think you might want to drink plenty of water afterwards also, to help flush out your system.
I know that all the stop smoking literature says it takes 72 hours for all the nicotine to leave your body when you stop, so 72 hours is probably a safer bet.
Talk to your baby's pediatrician or maybe a lactation consultant and ask to be absolutely sure, though.
Happy birthday to you!