I started in July 2004.
Only got the heat turned on this week. It's been a long and arduous process. Windows were 3 months late. Plasterer turned up 5 months late. Plumber still hasn't finished. At least the electrician has been reliable!
The project is 100% over budget. Some of that is self-inflicted (e.g. by upgrading specs and materials along the way) but a lot of it was due to poor planning and budgeting. Do your sums. Sit down with someone who really knows what's involved and add up EVERYTHING.
(Illustrative example - digging out a septic tank and percolation area and filling it with the correct type of stone/fill etc can take 3 days at €25 per hour for a digger and operator plus €500-600 for stone depending on your site - total cost additional to the cost of the tank and piping €1200).
I like to think I know my way around a construction site, and I've done extensive renovation/rebuilds before, but times have changed and labour is extremely scarce in the building industry.
If I was doing it again in the current economic climate I'd bite the bullet and wait the year or so (depending on what part of the country you're in) you may have to wait for the right contractor to be available.
Agree on a reasonable budget and completion date, hire an architect to supervise (it's amazing what people will try to get away with when you're not around) and have a contract and penalty clause to encourage the builder to complete on time.
And try not to change things too much along the way. It leads to delays, and the perception that the budget is going up can have a profound effect on subcontractors and how they deal with you.
If the job goes on too long everyone gets depressed and unmotivated so you'll have your work cut out to keep everyone on track. It's a vicious circle.
Getting started is important as long as your site isn't too wet. Try to keep it as dry as possible with plenty of stone/gravel etc around the site area. Nobody wants to work in a mudbath. Get your drain/foul sewer design right from the beginning, put down the drains and other service pipes (esb, gas etc) early in the site preparation process and/or make sure you leave openings in your founds or rising walls to get them into the house. I know this stuff sounds obvious but it's easy to overlook this kind of thing if you or someone else isn't on site looking ahead to the next stage. For instance I recently discovered no gas pipe into the house for the cooker. More digging required.
But best of luck with it!