There is no way to book earlier than 90 days. You have to call at 6:58am eastern to get the cruises. I booked the Wishes cruise b/c I think it offers a truly unique perspective. You are on the lake overlooking MK. At Epcot, you are in the canal below the bridge. For me, it was a similar view to the UK terrace or French arm which I could do any day. Also, you can usually watch the Electrical parade from the Wishes boats. Finally, there is always a risk with the Illuminations cruise that the wind will blow the smoke and ashes in your direction. The decision is yours, but this is my perspective. I really gave it a lot of thought before I called to reserve. I wish you the best for securing the cruise!
Edit: We reserved the premium Wishes boat with the music piped in. It is the same price as the Illuminations cruise.