Hello, Welcome to Just Answer and thanks for your question. If your partner is gentle and you use a lot of lubrication, there is likely no problem with having intercourse once before you see the gynecologist. Friction will irritate it further so it isn't something you want to do frequently. You might also consider oral sex until you see the physician.
Yes, I really meant only once. The more you have sex, the more the cyst is irritated and the larger it becomes. If the bartholin's duct is completely blocked then the cyst will fill still more each time you get aroused. That is the reason for the limit on sex. The "filler" can be lubricating fluid, or it can become infected. In that case it is called an abscess and it is quite painful. That would require medical intervention right away since even walking might be a problem.