Is it better to prepare the TM7 form and copies before visiting Chaengwattana Immigration for a 30-day extension?

Plenty places to print in the building, but get their super early and expect to be there all day.

There are two copy shops side by side in the basement of the building (really on floor 1) they can fill out the form, make your copies and take your picture.

If you get to the immigration office at about 8:50-9:00 you should be out of there by 11-11:30. People on 30 day extensions don't tend to get up early and in the afternoon that section "K" is jam packed with people.

You can get the TM7 form, photo copies and passport photos in the lower level of the building. When you go downstairs stay to your left. The shop will be on your right. If I remember correctly the photo copies and the passport photos cost roughly 100baht. Ask her for the form as well.

The problem at Chaengwattana is the queue. I usually try to get there before 7:30 so I can get a good queue (in the 150-200 range). Officers line you up making sure nobody is skipping the line. Then at 8:30 they open the doors and you get in to reach another counter where they will give you an actual queue ticket (if you have all documents in order). If you lose time filling the form (available only after they open the doors) before getting the queue then scores of people will come before you. I ususaly manage to be out by 9:30 am but that is only because i come early with all documents in hand (NB queue for extension is not as bad as the others)