I usually have wedding images edited down to 300 or so, and it takes anywhere from 12-20 hours to do the editing. That is with retouching/enhancements/resizing etc...I start with raw files, and end up with PSD's, Jpeg's for printing, and low res. jpeg's for website. They are then taken to my printers for 4x6 prints, which i pick up the following week and then get into an album and present the b&G with the following week...so usually about 2 1/2 - 3 weeks. My clients order enlargements thru me, and turn around time is about 2 weeks on those. If clients are only get CD's, i usually have it for them in a week - week & a half.
Yes, i could get my prints faster etc...but i do approx 3 paying jobs a week, (plus freebies), so I spend ALOT of hours editing, so I have one day a week for dropping off/picking up orders at my printers. One day for sorting/filling orders etc. I try to have edit every job edited within a week...otherwise i would be sorely behind!!! Over the spring/summer/fall months I spend about 35 hours a week just editing!!! not to mention shooting time and being a mother/wife.
Anyone who says 3 weeks is too long to get thier wedding pix if impatient and unrealistic.... Remember that most people who shoot weddings, also have another full time job to work in between....so expect reasonable amount of time. So , i guess in the end, 3-4 weeks is a reasonable amount of time to wait for prints, longer is you are an extremely busy photographer, maybe 2 weeks for cd's only. People have to realize that you have other jobs (photo or otherwise) and have to expect reasonable amount of working time.
And yes, write it into your contract.