How long can I legally stay in Thailand after my Non-B visa cancellation on April 24th?

Good morning, I’m being furloughed on 24 April and on that day my work permit and Non-B extension of stay will be cancelled at the One Stop Service Center. I am not clear how long after the cancellation I will be allowed to stay legally — I’ve heard 24 hours, 7 days, and 20 days -- but won’t know for sure until I report to Immigration on the 24th for the cancellation. I have been hired by another company to begin work on 1 May, however, I will be unable to leave (or return to) the country to get a new non-B. My new company is in uncharted territory as well, and has provided me with the following documents to take to Chaeng Watthana:

1. TM86, application for change of visa though it appears from my research that this is only for Tourist to Non-B

2. TM7 for extension of stay, though it’s my understanding this would be valid only for the visa that will have been cancelled by the time the TM7 is presented.

Can anyone offer guidance as to what I need to do to successfully stay in Thailand while my new status is being sorted out? Thank you in advance.