Dehavillanddriver,
I believe the letter from Virgin (if you get the nod) says something along the lines of "we expect your proficiency check to be no later than the end of (say) April". If you are able to obtain the endorsement on your licence before the month that they specify then of course anyone would. Its not about playing by the rules. Virgin gives you a date by which you must have the Endorsement. Virgin can choose to prof check you earlier if they wish or (like they are doing now) wait until the month they specified.
In any rate they will only check you when a position is available and due to a lack of aircraft at the moment they will hold off untill they said they need you.
Cheers
Tixy