I tell them it'll be about 2 weeks and usually deliver a blog post within a few days and the full edited gallery within a week.
The one and only wedding i did took a week to edit, and to be honest i wish i had given myself a longer time frame. I didnt have any rushed edits slip through, but it put me under more pressure than i needed to be. A week of photoshopping 6-8 hours a day is no joke, i found it exhausting.
I can now process a wedding in about 6 hours, from CF cards through Lightroom to disc. I avoid using PS.

Those 6 hours are often spread over a couple of evenings, some evenings I have other shoots to do, clients to meet, beer to drink, tv to watch. I'll leave an edited wedding for at least a day and then review it again to make sure I've not missed anything before I burn to disc.