I am no expert but If it was only 2 months he should start feeling better after today but not totally himself for up to two more weeks. Rehab is Good if you guys can afford it. The first time I abused was only 2 months (a long long time ago and I was WD for 7 days but was feeling better after 4-5). Be very thankfull you cought it this early.

If he's going to an in-patient, medical facility, you should check to see if he needs to be clean when he gets there.  Most such facilities don't expect that and w/d is a lot easier to take on the inside with medical assistance than it is at home.  

That being said, if he was on 20-30/day, it's unlikely that he's going to be done with w/d by the time he gets there anyway if he's going this week.  It generally takes over a week before folks on higher doses begin to feel human again.

If it were my loved one, I'd keep them on just enough hydro to let them feel human until I turned them over to the pros.  There's no need for a big binge before going off to rehab (although many addicts (me included) try that, so don't let him be in charge of the pills), but there's little good in going through hell when you're just about to hit safe waters.

Once you get him into the hands of the professionals, you can know that you've done the best and most loving thing that can be done for him.  At that point, let go of it (at least until he's done) and take care of yourself.  He may be the one who is physically sick at the moment, but this is no less trying on you on an emotional and spiritual level.  

It may not seem like it at the moment, but all of this can turn out to be a very good thing.  The discovery of my hidden addiction and having to pack me off to rehab (twice) was very hard on my wife.  But we have both grown in Recovery in ways we never imagined and now have a better life together than we ever thought possible.  Not just better compared to the days of active addiction, but better than ever.

Does this facility have a detox in it? If not he should be completely detoxed before he goes in. I went to a rehab that didn't have one and I wasn't detoxed yet. It was hell and i didn't make it. I had to leave and go get detoxed. I ended up just staying messed up for a few more years. I wish now that I had gone in there prepared so I didn't waste all that time being high afterwards. Also, like the above poster said, it is much easier and safer to get detoxed by professionals who know what they are doing. They keep you comfortable and it's not so scary. I wish you and him well. (((Hugs)))