Park hours for January should be out around July 1, which gives you at least 6 months advance notice.
ADR's are made at the 180 day mark.
So in many cases, you have the park hours, slightly before the date you make your ADR's.
We are going from Nov. 25 - Dec. 2. The Nov. park hours were released the first week fo May and I can't make our ADR's until May 29, so I've had a couple weeks to work out the details. The only problem is that the Dec. hours won't be out until the first week of June, so we are running into the ADR's prior to the park hours for one day (travel day, we don't really count figuring we won't do any TS that day)...but, we already decided that for Dec. 1 (hubby's bday), we're going off-site for dinner at Emeril's.
It's usually not too much of a problem and you do usually have an idea of the hours based on the historical past. The DIS does list the historical hours also, so that will give you some idea if you really do run into the overlap of ADR's before park hours.
If you are going mid to late January, you shouldn't worry at all because the park hours should be out before you can make your ADR's.
By the way, here is the link to the Hours page here at the DIS. Park hours through Nov. are currently available. You should also be able to view January 2007 hours, which could give you an idea of what hours might look like for January 2008. You can also plug in your dates and they will give you a tentative park hours chart.
http://www.wdwinfo.com/wdwinfo/hours.htm#hm-parkhours-quicklink
