I personally wouldn't put her in a brood buster with 25 degrees at night. She might get overly chilled.I suspect that one of my Welsummer hens is broody (this is my first year with chickens and have never had a broody hen before. She is only 8 months old...). She has plucked out all of the feathers on her breast, has been in the nesting box for 2 days (though I have been putting her up on the roost at night, last night she threw a FIT, but stayed up there). It has been freezing here lately (~25degrees at night), so I am torn: do I put her in the broody breaker, or do I order some hatching eggs. How long should you wait to see if a first time broody sticks, I don't want her to give up on the eggs after a few days....?
I actually prefer not to discourage a brood as I never know when I'll need that hen to hatch some chicks for me and figure if I get her in the habit for being discouraged about brooding, she'll not stay the course when I need her to. If I don't need chicks, I just let them stay the course until they quit unless they appear to be seriously risking their health (I've heard of that happening, but I have not had that happen...if they are still lively...as far as a brooding hen is "lively"...ie look well enough and alert... I let the brood run its course.)
I have gently encouraged hens to leave an extended brood by gently lifting them out of the nest box and putting them down in the yard next to some really nummy treats. I repeat this a number of times in the day...usually by a few days they run to me when they see me and in a week are out and about again. Really nummy treats is the key and the reinforcement for not being in the nest.
As to whether or not she is serious and will stay the course...that is hard to know with a first timer. I can usually tell after 2 or 3 days if a hen is seriously brooding especially if they have plucked their breast. I have waited a week to be sure with a new hen, but some new hens stop sitting at the end of 3 weeks no matter if there are unhatched eggs or not so if I have over delayed getting eggs under them I've got to trade another broody or would need to incubate.
As to ordering eggs. If you want some new chicks...then order them...just not expensive ones in case she doesn't go the course unless you have an incubator you want to crank up.
Brooding in winter is a little trickier due to the cold. The hen and chicks should be out of the weather and drafts and separate from the other hens. Be sure the chicks can't get around a blind corner or through a small hole and strand themselves away from the warmth of the hen. You also need to be sure the food and water isn't freezing.
I've had a broody hatch in cold February, and I was amazed to see mom and chicks do fine. The little ones were running around in the cold within 5 days scratching with the big hen. Of course I had them in a sheltered coop and run (enclosed building) but I did not have light or heat for them... and while I didn't have snow on the ground it was getting very cold at night...below freezing...and not getting much above freezing during the day. It's the craziest thing to see them run around as if they never knew they were suppose to need heat lamps and a controlled environment.
Good luck no matter what you decide.
Lady of McCamley