If you’re talking about rooting roses from cuttings, it will depend
greatly on the method you’re using. Roses are rooted during the growing
season. If you’re using a sophisticated misting system inside a greenhouse,
it will usually take at least several weeks, maybe longer. If you’re doing it as a backyard hobbyist, it could take several months. Some varieties are easier to root than others. Roses can also be budded onto root stock, which is a whole different process. The majority of commercially sold roses are propagated onto root stock.
I’ve rooted a number of roses over the years, but always as a back yard hobbyist.