Find a long flat road and do a couple of practice 40K efforts with the same bike setup you intend to use during the race. If you can't find that much unbroken road then do say 4x10K or 2x20k or other variations but on similar terrain and the same bike setup.
Do these efforts starting from a standstill with one foot on the ground. Starting a TT well and getting up to speed smoothly and quickly without burying yourself in the starting effort is a skill that many folks need to learn. Practice that before the event.
Start easy - finish hard for a 40K. You'll be out there for somewhere around an hour. Don't blow it in the first five minutes by going way too hard. Sure don't roll out looking at the flowers but find your sustainable pace for an hour and if anything start a bit easier and ramp into the effort over the first five to eight minutes then just ride hard to the end paying extra attention the the second half where many folks fade and lose concentration.
Don't take too much rest in the final days, but you won't gain any measurable fitness in the last three to five days so lighten up the load, take some rest days perhaps two and three days before the race, keep your legs loose by riding in the final days but not too hard (you're not going to gain fitness in those final days but you can wear yourself out and ruin our race) and get a good solid warmup including some race pace efforts the morning of the race.
If you'll ride in aero bars then start practicing in that position or you'll likely lose a lot of power on race day. Keep your head tucked (a.k.a. turtled) when riding in the aero bars and that also takes practice before it feels natural.
Good luck,
-Dave
