I'm sure it'll be better than nothing, but how much it helps depends how much you've been doing and how long. When I had a little baby habit and was snorting about 5 bags (mediocre east coast powder) a day for a few months I got through w/d fine with about the same amount of sub u have. I would start with maybe 4 mg the first day, and then maybe another 4 the next day and then 2 and then 1 and then you're pretty much good.
If you have a bigger habit, you're probably gonna need a lot the first day or two. Since it has a naturally long half life, even if you need to take it all in the first two days, it'll stay in your body a while and let you down pretty easy
***You need to wait at least 12 hours after your last dose to take the sub, or it will just make it worse. This is super important, you need to really be in w/d to take the sub. the first day, start out small and take more until you feel better (it takes 30-45 minutes to kick in sublingualy) the next day do the same thing, and after that work with what you have left to taper down.
If you have a big habit, think about finding a sub Dr, if you don't want to be on maintenance, you can taper off right away