In reply to AymanC:
I get this, not as bad as some people but a lot worse than most. Warming up the fingers and staying warm (whole body and hands) is key. Indoors I start off on some easy boulder problems in rapid auccession, then do a few medium difficulty ones with rests in between. The idea being to 'shock' the fingers into working hard, then the blood returns while resting. Doing just easy stuff isn't enough.
So in your case, if you RP 7c, warming up on 6b+ or 6c probably isn't hard enough to get your fingers working sufficiently hard. May be do one of those and then get on your project and do it bolt to bolt with decent rests.
Outdoors it depends on what's available but similar principles apply if possible. Also avoid going to cold crags which are in the wind and don't see the sun. I actively seek out warmer crags unless the valley temperature is in the high teens or above (even then I won't go to shady mountain crags unless it's a pretty hot day). Plus I don't rock climb at all from about mid October until about the end of March. Simply not worth the bother. That's ok for me as I can go winter climbing, dry tooling and alpine spring climbing or ski touring instead.
When not climbing, if it's chilly I wear thin or medium weight gloves, including for belaying.
Avoid overgripping and shake out as much as possible. I find this is particularly important when winter climbing.