When will you compete with out a head guard on? You'll compete in the Amatuers first and that will be with a headguard (not a full face one). I find Sparring head guards restrict your veiw slightly any way.

Your best bet is just to enquire and ask the doctors, it may be a case of you having to wait a few days/weeks/months, it may be a case of not at all.

No harm in asking them, they're not gonna charge you for advice like that if it meens you don't get the surgery