Four months is the rule where I take my girls. By eight months, they must be spayed or neutered. Rory started at four months and has been going ever since (and of course as soon as we adopted Lane she started attending as well).
I actually credit daycare with teaching Rory it was okay to use the bathroom outside. Since we live in an apartment, she was always pad trained. Poor thing would go for really long walks without going and then as soon as we'd walk in the door she'd rush to the pad to relieve herself. I'm sure it all depends on the type of place it is, etc. I am lucky enough to send mine where they actually have real grass play yards which probably helped her to make the association. Likewise, Lane was rescued from a puppymill at around age 2 and she quickly learned to use the bathroom outside (at least at daycare) and on walks within a month or so. The pad training around here has dramatically improved, but I think that is just due to our consistency. I hope I didn't just jinx myself!
Good luck!