My visa based on marriage will expire on Wednesday. My wife's next day off from work is Friday. Would a couple of days be alright, or should I have her take off of work on Wednesday or before.

Thanks in advance.

If you have an Extension of Permission to Stay based on Marriage to a Thai, then don't leave it until the last day - better you go up to a month before.

In your case go tomorrow (Monday), get your wife to take the day/morning off as a matter of urgency, or Tuesday at the absolute latest.

This, at least gives you a chance to fix things you if you have any problems with the paper work.

Do nothing and after Wednesday, you will be staying in Thailand illegally, which will cost you 500 THB per day and get some ugly stamps in your passport!

You could have applied any time during the last 30 days.

Not always a good idea to leave it until the last minute.

As said go today in case of problems.