Hey Gazza,
i would say, take into account why your doing it. If, like me, you love fishing and being on the water, and if it was going to keep me off the water for a long period, never!! So, I would need a second boat to use while working on the project to get my water fix. I'd never do it now, maybe when younger, I did have a mate plant a cruiser in my backyard for "2 months" to do some work which was there a hell of a lot longer than 2 months. Good mate so I didn't mind.
No such thing as a time schedule, too many variables. If you just love projects and working all good, but on good weather days, where it would always be a toss up to go fishing / boating, or work on boat, in my case no work would get done.
Motor would be the last thing I would buy in case it all goes to shit, in 5 years there may be a whole lot of options to power her you wouldn't have had originally. Even if you resell the motor it is 5 years older and never been run so resale an issue.
If I was to do a project boat I would do a cheapie throw away, get my skills up, then tackle my dream boat.
Just opinions of mine, I only do wiring, small add ons etc, no glassing or rebuilds so my opinion lacks experience. I do admire those that achieve it, but in saying that I would probably never buy a rebuilt boat no matter who did it. I respect the ocean too much and have grandkids