Thank you so much!You need to work with your current employer for a full year before you'll qualify for the 50 points. So the answer to your question is no regarding your current job.
Same for your previous employers (i.e. you can't claim the 50 points). You are no longer working for them so not possible to claim job offer points for these roles.
You need to wait 9 more months before it will be possible to claim the 50 points since you are on an LMIA exempt closed work permit.