Building a custom house is great if you can do it at an affordable cost. You already realize the time frame is going to be longer than the end of May so your expectations may be realistic.
Assess your wants and needs. Are you willing to show restraint to fit the house to your budget? Often, once the house is underway, people want to upgrade to fancier tile, better appliances, wider driveway, second floor on the garage, and find they are way over their heads in debt. Do you have the time to be at the job site frequently? That is a must to assure you are getting what you want and that plans and drawings are properly interpreted. Be aware that you pay for changes along the way too. When you say, 'yes, the sink should really be on that wall, " it can cost you hundreds of dollars to move it.
I'd like to build the house of my dreams, but I can't afford it the way I want it. The house would not be huge, but it would have top quality materials and cost double what a comparable average house would cost. So, I'm happy where I am and I've done upgrades along the way. .
If you buy an existing house it is what it is and can be modified. If you contract for a house to be built, it will probably cost a bit more than the original contract because of changes along the way. If you build it yourself, it can be a crap shoot.
I know of one couple that built their first house themselves, moved in to it and six months later started on their second house to avoid the errors of the first one. They sold the first at a nice profit though, a winning situation.
One of my friends built his own house 15 years ago. It still does not have doors on a couple of closets. Initially ran short of money then never found the time to complete.
Every custom house ever built has some stories to it. Listen to some so you can avoid the really dumb ones and take advantage of the good tips.