Just be mindful of your shearers, who should not be exposed to Crovect applied within the last few weeks. (Many say within the last four months.)
Keep all sheep clean and tidy, so be on top of worming and dagging.
If flies are about, select open breezy locations for susceptible sheep. But with shade - just not still, humid shade.
Nothing to stop you Crovecting lambs if they’re old/big enough, as they won’t get sheared this summer anyway.
Keep your eyes open for greenbottles. Once you see a couple or five of them in a day, probably time to Crovect the lambs at least.
Downside of early Crovect is that you’ll probably need to apply it again in eight-ten weeks. And just maybe a third time, depending.