Toddler Signing

If you taught your LO to sign, how long did it take for them to pick up on it? I've been teaching LO the sign for "milk" for about a week and was just wondering about how long it'll take him to start doing it.

I know every kid is different, I'm just wondering  
We are doing one sign at a time also.

We started trying to teach him at like 7 months old, and it was just between 10 and 11 months that it was like BAM it clicked and he could sign everything.