My mother owned her own child care service when i was little in the early 90s and in the late 90s and early 2000s she was the board director of a day care. She also has been certified in cpr, worked for the american red cross and was a CNA... so honestly not long at all. I let her watch my daughter at like 1 week old but some people are different. I just knew shed be safe with my mom and dad. My dad was a volunteer fire fighter and had to know cpr and first aid also so it really wasnt a big deal to me but ik some moms arent that trusting.
My advice as a mom with a lot of kids lol. Start now, so your baby can be use to being away from you sometimes. I have NEVER let anyone watch my kids besides my family. Only my mom, mother in law, sister in law, my sister. Never any friends.
You just have to trust whoever your leaving baby with.