Monday December 11 sees another public holiday in recognition of Constitution Day. All government offices nationally, including immigration, will be closed and will reopen the following day at 8.30 a.m.
Chonburi (Jomtien) immigration tends to be very busy just now before and after a public holiday. Hence, the working days Friday December 8 and Tuesday December 12 are likely to witness overcrowding, especially with the weekend intervening prior to the formal closure on Monday December 11. Best to get there early if you must!