I would contact a windshield shop- those adhesive kits never hold strongly enough. You need to be able to glue that disc on there, and then twist the mirror base onto it- a lot of force, and the glue doesn't hold up. It needs to be specially cleaned and prepped.

If you feel that you want to attempt it, and your kit includes a cleaner, I would follow the instructions implicitly. If there is no cleaner included, I would at the very least scrub it down with an alcohol wipe (window and button). Remove the button from the mirror, if you try to install it with the mirror attached it will have too much weight on it to be able to set up correctly. As is, even after 24 hours the adhesive may be "set" but it has not yet "cured", meaning there is still solvent evaporating out. I would let it cure for a week or so before attempting to mount the mirror. The mirror is mounted by putting it in place at a 90 degree angle, and rotating it until it locks into place.

If it doesn't look like you feel comfortable with it, don't be afraid to at least consult a professional and ask them- most body shops also include glass installation services or have access to preferred contractors.