We've been mostly lucky.
For DS1, referred in the December of 2006, first appointment with community paed early February 2007. SALT about 2 months later with weekly therapy sessions starting at home in the summer holidays.
Meantime, we had a play assessment with Durham CAMHS over several days in June and a diagnosis a few days later. OT were the odd ones out, as it was almost a year after that before they would see him, in May 2008.
Post-diagnosis he was transferred to our local area CAMHS, who saw him in the September, but didn't really have anything useful to suggest. Said they'd call him back in 6 months. Ended up being 9 months and they signed him off.
Cut to early last November DS1 was obviously having difficulty with his ADHD, so asked for a re-referral to CAMHS. Finally saw them in early February and told the process would take 6 weeks. It was mid-June when we finally got a diagnosis and some treatment.
He was re-referred to OT by school, early this year and we finally had a first appointment, last week.
DS2 never had the long waits for OT that DS1 did and we've not had to deal with CAMHS for him, so much less frustration there. His referrals to PT and subsequently to orthotics were both through in a matter of weeks. We also "only" had to wait 3 months for a portage slot for him when we first had him referred for evaluation.