We were really lucky with Blue, got him at 11 weeks, and he was used to being in a hutch with sawdust, so we already had a litter tray and just put sawdust and hay in it and he took to it straight away (really lucky i guess) although he does like spraying the sofa (3 times in total which is not bad in 3 months, must be a monthly thing lol) as he's just coming into maturity but being neutered in next few weeks.....!