Now you can add the construction adhesive. Add a liberal amount because this is going to have to hold the timber in place, but it also fills any voids if the surface is slightly uneven.
As a general rule timber will move with seasonal changes. In most cases you need to allow for this but with this method we aren’t allowing the countertop to move at all. This is fine provided to use enough “fasteners” to stop it from moving. Because this kitchen is indoors it will only be slightly affected by seasonal changes, but you still need to make sure there is as much glue applied as possible (without putting on so much that it squeezes out everywhere).