Daniel got his first flu jab last year, he's just got his appointment through for this years, so I don't think they offer it before they're 12.
Dan is supposed to go to asthma clinic every 3 months (height / weight and peak flow readings). Alex goes once a month, but once he turns 1, he'll be every 3 months as long as it's under control. We've just had extra appointments for them both as Dan gets worse in autumn and Alex is a bit chesty.
Up until a couple of years ago, our surgery used to ask Dan to go in for an appointment after every 3rd repeat prescription, patients have found it easier when they have set intervals though, so they've stuck with that. Rather than seeing the GP, they see the practice nurse first come first served so it's a lot quicker than waiting for a set appointment which ends up an hour late.