usually its decided for you when you will deboard, if the WCs arent there then you will wait and probably 1 of the last ones off.
If by 'We' you meant 2 of you then usually they will use I think the Crew lane to process those in WCs etc, no waiting in the reg line if my memory is correct.
However if theres more then 1 other person besides the person in the WC then I believe everyone else (but 1 extra person) will have to reg line it. So if you are flying as a party of 4, 2 of you will most likely be told to go on the reg line. It really doesnt matter as it usually takes a min of 30 mins or so till the bags start coming out, so the only question is where you wait on the Imm Line or by the carousel