Is It Legal to Teach in Thailand Without a Work Permit While It’s Being Processed?

After taking the advice of people on this forum, my friend starting searching for teaching jobs to tide her over until she turns 50 later this year.

Now, a private Thai language school in Bangkok wants to hire her immediately (she has a degree in child development, and has taught in schools previously).

She will insist that the school immediately provide a letter and supporting paperwork so she can get a B Visa before her current ED Visa runs out in March (which we've heard only takes a few days, assuming everything is in order).

Here's the question. They said her work permit will take two months to process. Yet, they expect her to start teaching immediately... before she has a work permit in hand.

In fact, her employment contract mentions a 3-month probation period BEFORE they apply for the work permit (to protect the school in case of "contract breach." )

My research indicates that most schools do this. I've read conflicting accounts on immigration's stance on this common practice: some say it's ok to teach while the work permit is being processed, others say you can be deported (assuming immigration visits the school).

What's the best way to proceed here? Any advice would be appreciated.