I voted 6-9 months....I couldn't really remember, but it was somewhere in that time frame. We couldn't get Mojo until about 3 months or so (can't remember that exactly right now either)
BUT, we had a groomer then, that we could stay w/ the whole time.
When she "retired" --due to cancer--we went to another and I didn't know it was a drop off one.....I took him in and sat down and she told me it would be about 2 (went in about 9:30) when I could pick him up.....we went ahead and did that, but that was the last time --ever! No problems w/ it, just don't like the thought of him being in a strange place and in a cage all day!
We now go to a groomer (on and off) that allows me to stay w/ him....it only takes 30mins for everything or about 15 or so if just a trim up and bath. She does a good job. I normally do it myself, but like to go for those "special occassions" or holidays. The "inbetweens" are done at home.