If you ride all year round, then there may be a better time to service than in spring, when bike shops start to get busy.
I sevice mine in Sept, before the winter weather sets in.
You could take your bikes in when he is really quiet, usually after Jan sales. The mechanic may have more time on his hands.

Handbuilt wheels are vital for a reliable bike , and a spare set of wheels (or 2nd bike) will keep you riding whilst you fix it or get it repaied. My commuting wheels are handbuilt from low-end components. They are very reliable and tough.