Meibomian glands've been clogged for 3 months but now i am starting warm wet compress once a day and doxycycline. how long until the glands unclog?

Varies : It all depends on how serious your meibomian gland dysfunction is. Most of the time there is noticeable improvement in symptoms in 6-8 weeks with the treatment you've described. Make sure the compresses are from a microwaveable gel pack that stays hot for the 10' of application. Also, occasionally a combo antibiotic/steroid ointment may need to be applied to your eyelids at bedtime. Good luck.