I developed tooth abscess 3 days ago. I'll see a dentist in another 3 days. Do you think it is ok to wait until then or I have to see him earlier?

Don't wait! Any infection can spread quickly, causing very serious complications and can even be life threatening. First, your dentist has no way of knowing how dangerous it is without seeing you, and secondly you need to be placed on an appropriate antibiotic immediately anyway! we make sure we see our patients the same day. If your dentist can't see you, find another one, at least for this emergency.
Never wait . At any age, depending upon which tooth/teeth are involved and the source of the abscess, it is not advisable to wait if there is any swelling. If you have difficulty swallowing or breathing, seek emergency care now. You did not say if your dentist diagnosed the abscess or you 'think' it's an abscess because of pain or if you will be seeing a specialist. Good luck to you.
Emergency. An abscess can become alot worse in a short period of time. I cannot tell how bad your problem is, but the longer you wait the bigger risk you take.
Should be OK. It should be ok to wait a couple of days, if all you have is pain at the site. If you start developing other symptoms such as fever or much worsening pain, i would get seen asap.