If you use 204 c support letter and it will be a close work permit. The processing time is 88 or 89 days. ( check IRCC website)
If you have submitted your PR application and received your acknowledgement of receipt from IRCC, still in Canada, your work permit expires in 4 months or less. Have NO employer restriction on your nomination.
https://www.canada.ca/en/immigration-refugees-citizenship/services/work-canada/extend-permit/bridging-open-work-permit.html
You can apply for BOWP. Otherwise stay on support letter!!
I got BOWP refused three days again. I need to restore my status with 204 letter.