reviewers are developers often busier than you :) so if you cc them as soon as you push the patch, "they can't do anything" since the ci hasn't finished. what if the ci fails? they will get a notification too and they can't do anything, and you just wasted their time.
so, ask others for a review (cc them or message them) only once the ci passes and you want a final thumbs up from them. asking for help is different from asking to review, if you are stuck and have exhaused quite a few approaches, you should ask for help. see reading others' code