Gracie was about 4 months. She had very little trimmed though. We just wanted her to get used to going to the groomers-the noises, etc. She goes now about every couple of months just for a little trim-she gets her ears tipped, her nails clipped and her bottom cleaned up. We are letting her grow her coat out. We are very lucky. I brush them morning and evening and she just doesn't mat.
Just to add I think that Bristol has a much thicker coat and I can tell that she will likely mat much easier. We are getting her used to brushing now-in the morning we put her hair up and she gets brushed and inthe evening we take her itty bitty top knot out and she get brushed. The first couple of times she didn't care for it but now she doesn't mind at all.