In this post I'm not talking about bugging out because of a fire, I'm talking about your bug out fire.
A couple of things on this.
First, as I've said in the past you need to have at least 3 methods of making fire NOT including the matches that you should also keep in your bug out bag. To me a match should be used only as a last resort.
Second, once you've built a fire during a bug out, it should not EVER be allowed to go completely out. It needs to stay burning. Having an actual burning fire of even a very small size means it's far easier to build a roaring fire for something should you need it (like an injury).
Having said that, keep in mind that during the day smoke can be seen from quite a ways off, especially in the mornings. Therefore, your fire should be allowed to get quite small once the sky begins to brighten so that any smoke is dissipated and not visible anymore only a foot or so above the flame.
A word of caution about keeping your fire burning. Doing that may mean keeping a "watch" awake at all times. If your group is larger than 5 or 6 people this will be fairly easy. If your group is smaller that will make keeping your fire burning constantly AND thinking about reducing the size of the fire before it can be seen as morning comes a bit challenging.
If your group is very small you may want to consider trying to combine with another small group.