Lay the counter into place and center the base cabinets beneath. Mark any overhang that is longer than 1 inch for removal. If one end of the counter will touch an appliance such as a refrigerator or oven, mark it at 1/8 inch.
Lay the countertop upside-down on your workbench and trim it to size with a jigsaw. Trace any templates for sinks or other openings onto the back of the countertop according to the directions for your particular installation. Cut out the openings with the jigsaw.
Glue the endcap battons in place with wood glue and apply padded C-clamps to hold them as they dry. Remove the clamps after 1 hour and sand the battons smooth. Apply the endcaps to the battons with a warm iron and let the countertop cool completely.
File away any edges of the endcaps that extend past the countertop. Place the countertop back onto the base cabinets and center it. Insert ¼-inch shims at regular intervals between the countertop and the cabinet edges.
Squeeze a bead of all-purpose construction adhesive along the base cabinet edges. Slide out the shims so that the countertop settles onto the adhesive. Let the adhesive dry 24 hours and wipe down the countertop with a damp cloth.