My neighbors used incandescent and their chicks (we're talkign 6 total) were fine.
We started w/ incandescent last spring & couldn't get the 3 chicks warm enough. I broke down in about an hour and rushed out to get them a heat lamp. The heat lamp we got was white and our chicks were fine. They're all adults now.
Our most recent brood consists of 2 chicks and we're using a red lamp. I find that the chicks are often awake at weird hours - like 3a when I got up to tinkle this morning. They are, however, just as often asleep during the day.
I don't think it really matters either. Last year I used a white infrared bulb and they seemed to thrive. I put them by a window so they also had some natural light but didn't buy the red light as we had started with these.
This year, I have the red but it is more because that is what I had on hand when the chicks came in. It's warm enough that the adult birds don't need it in their house.
I have only ever used incandescent light bulb which I keep on 24/7 for at least the first 6-8 weeks. The heat lamps have always gotten way too hot for mine & I'd be afraid of burning the place down.
I am even cautious using my big incandescent bulb, the 150W. I measured the temp under it, and it was 111 F so I took it out for 100 W which after the first week, I brought down to a 75W this second week and next week down to 60W. The chicks sleep just fine with the 24/7 light. The problem comes when they experience their first dark night; they always cry a lot.
You should use incandescent light or another heat source for at least 3-4weeks. If they are outside then longer. You can get red or tinted bulbs but I've only had to use them once. I had one bored batch that started picking but I've never had another problem. There are also little screw in heater things that run off the incandescent light socket but don't produce any light. However they are expensive. Majority just leave an incandescent light bulb running 24/7.