In my experience, postponing a build with the expectation that things will be better/cheaper in the future rarely is a successful strategy. If your present home is one that would be attractive to a family, bear in mind that families don't like to uproot their kids during the school year, so your best window of opportunity for selling your existing home would typically be late spring through early summer. however, there's no reason you couldn't put your home up for sale now and be upfront that you want a lengthy closing period. We bought our current house in early October and were told the earliest we could close was in January. This worked out well as our existing house took a while to sell.

You're juggling a lot of balls and the likelihood that everything will come together on your schedule is small. My advice would be to start the build ASAP if you can and hope that it comes in on schedule. The option to stay with family if the build takes a longer time than you plan and/or you existing home doesn't sell when you want it to is a luxury many don't have.

Also keep in mind that the market is changing and is slowing down in many areas including some of the hottest markets in the US. Waiting to sell your current home may be more difficult next year.

Do some research. I feel homes sell better in the spring, since moving in the fall is impacted by coming holidays. My youngest just moved(August), the sale of the old, purchase of the new, and the actual move was interrupted by a long scheduled, non refundable vacation.

However, building is impacted less by weather in the summer. Winter is a really difficult time to start construction because of snow/cold and rains in spring can slow progress. Often the quality of the build areas is impacted by weather. Like shingles. The absolute best time to install asphalt shingles is on the hottest day of the year, so the adhesives work best. Shingles installed on cold days will impede that adhesion. Framing when wet can impact boards, pouring concrete is different depending on temperature/rain/snow/etc. Those areas are optimized in summer.

Prices for materials are so variable, predicting them is best guess(SWAG). And those prices can change daily.

There are approx 60 line items in my cost breakdown and one of them is lumber.

My overall costs to build a home have increased regularly over the past 30+ years at more than the rate of inflation.

The exception was the last quarter of 2008 when suppliers cleared materials below replacement costs.

Sometimes it pauses, but rarely decreases. we are seeing tarrif impacts now.

Good luck.

We have always taken the most conservative option, selling the existing home and moving into a rental. This creates the most flexibility financially. You have eliminated all of the unknowns of selling a home. This will allow you to build in a more leisurely fashion.

The Chicago market never rebounded from the bubble crash. Is there no existing house you could buy? (Much cheaper per square foot than new.) Where do you want to live? Do you own a lot? Is this a a custom build? A development? Plans? Price range? Lots of factors.

My local market (far north shore) is down 0.8% this month and dropping. I can see five beautiful, newer (and unsold) -- $1 - 3M homes from the foot of my driveway. Two are foreclosures.

I wouldn’t wait. Lumber is only one piece of the puzzle. Other factors will probably continue to increase. Tarrif wars aren’t helping either.

"Requesting May Delivery" is now 8 months & 13 days away. Assuming permits and full crews are at your disposal Monday, this is possible.

"We're lucky enough to have an option to stay with family if needed in between."

I think that qualifies as an oxymoron.

Most builders will guarantee completion by a certain month as long as the year is not specified.

Sell your existing home and then start your new build, unless you can afford to carry both mortgages for a while. Buyers "contingent" on the sale of their existing home to buy a new build are risky prospects for builders. You may expect any number of things being contingent; limited to production builders (some small builders don't do contingent), the builder may not start construction until you get a contract on your existing home, a hefty deposit will be expected,etc. Contingent buyers are "wanna be" buyers and every builder who has been around a while has been burned by one. If you qualify to carry double mortgages, then you can try to buy/sell at optimal on both sides and do as you please. Regardless of what's happening with lumbar, don't bank on home prices dropping.