As long as you are sure they will give NOC go ahead...start looking for a job.

But remember NOC is mandatory to get new job...if you don't have it or can not provide it; you will be subject to Visa cancellation by current employer and sent to you home country and will be banned for 2 years re-entry Qatar.

Also remember there is an article in the labour law that says you must cover one full yr with current soponsor.

Regards!!