Buddy's 4 months and ive been brushing him since we got him at 7 weeks, obviously very gently at first. I probably only take about 15 minutes a day, and thats brushing and cleaning his teeth and wiping ears and eyes! Within an hour he looks like a scruffy pup again but at least he's not got any knots. He's quite good at being brushed as long as you let him chew something while you do it (saves my fingers!) I found giving him bits of a pet tab while I brush him keeps him happy.