2 at a time or does it have to be all 4?
 

I've got some new coilovers. Well newish, an a free day next tuesday I want to get them fitted but I'm worried if ill have the time to do all at once so wanted to know if its ok to do the front/rear an then drive on them until I have time to do the others? It would only be a week or two between them. Never done them before and I know the top plates on the rear need swapping with my old ones so unsure as to how much time this will add on

Ste

I'd probably try to get all 4 done. But to be honest if you have a free day i dont see that you'd struggle for time.
Its a pretty quick job really, assuming all the locking collars etc are free to move & not seized, i'd check that before starting the job :)

What or where are the locking collars located? I've watched a few videos on how to change them and I'm handy with a spanner but just a bit worried how long it will take especially the rear top plates

By locking collars I just mean the ride height adjustment rings, you say yours are new ish so should be ok.
Pretty sure the rear top mounts are a very quick swap over, mine didn't take long but it was a while ago to be honest.
Sorry I can't offer more specific advice about that bit.
James