I personally think not working as a nurse while your application is on going is risky. I think it's up to you na lang po if what is your priority, your experience or learning french. More often than not, the IO will be asking kasi for updates for your work experience and its proof like SSS. I believe they are looking for consistency kasi and to know that you are continuously practicing your profession. You can claim additional points for this unless naka 8 points ka na sa work experience which is the highest. For the French naman, it is also important to equip ourselves with it before going to canada so that it will be easier for us to assimilate ourselves there and para din hindi tayo mahihirapan maghanap ng trabaho. Plus factor din yan sa selection interview. Pero we should be willing to spend money for it kasi let's face it, mahal talaga mag enroll in a french class. However, if you can wait until you get your CSQ before enrolling sa Alliance, I've read na Quebec will refund what you've paid for the class when you get to Canada. Not to mention na when you land there, they have free french lessons and may kasama pang allowance.
As for me, experience is my priority since 4 points pa lang ang meron ako. But while gaining experience, I plan to learn french on my own kahit basic lang and other simple conversational sentences. Saka ko na itotodo pag for interview na ako. Hehehe ;D