Travel planning before train schedules are released

From my reading here, it seems that schedules for after that date may not get posted until midway through our trip

You will be able to buy tickets at least 90 days before you get there depending on the specific route.

Any idea on if we will just have to wait until day before/day of to book the trains in the second half of the trip?

You will be able to plan and buy your train tickets at least 90 days before. You won't have to wait until you get there.

Check the schedule again in the 2nd week of March. But it does depend on the route. Which route are you taking?

If it is a regional train, or your connection includes a regional train, it may be close to the June 9 date before it shows up, but Freccia, IC, and Italo trains should show up at least 90 days out.

Since regional trains are always the same price, unreserved, and the schedule rarely changes significantly, that should not be a problem for you.

You can expect future schedules to be similar to current schedules. Railways are built around the schedule the railway intends to operate, and only when new infrastructure comes on line are there big changes.