If you missed the last ITA by a whisker (difference of max 5 points), you can wait one month more before sitting for next IELTS exam.
But if you are no where near the points required in the last 2-3 ITAs, it's better that you sit for the IELTS exam.
I am not sure when OINP will open as they have huge number of cases pending from 2015. I got my nomination after an year.
SINP and NBNP program get close very soon, you need to be on your toes when you apply for them. If you are in the job category they require, then try your luck.
Wish you all the best