Yes
@nimmau2 6months was what I applied for and was granted. You should do same even if you're expecting your work permit tomorrow or anytime soon. There's no need to seek for less than 6months since you are paying same C$100. Good luck
FYI: if your PR application is going well I don't think you need to apply for extension because you should be on implied status. I had a week before my stay expires so I did mine extension application earlier like a day after my Spousal sponsorship was received by IRCC in case my application had any error and is returned so I could still resubmit them with my OWP. If not I will not be able to resubmit with OWP after error correction which was not my case. But my application was perfect so the extension was just a back up. If you have escaped return of an error applications from IRCC then I will advise not to spend the extension money for nothing.