My rifles use either a regular scope with clip-on thermal or the rifle has both a regular scope and thermal I QD between. I use a visable laser to zero the thermal from the regular scope.
I go out at dusk and match laser zero to regular scope for distance I want to zero thermal. Then I add clip-on or swap QD Thermal and zero thermal to laser. You cannot see a laser through a thermal, but it is easy to go back and forth or have a buddy with binoculars calling out where the laser is hitting compared to thermal aiming point.
In one case my rifle has an IR/Vis laser permanently attached and it is best. Not only can I hunt IR laser with PVS-14 left eye or thermal scope right eye. I can also use the IR laser to show a friend hunting NV game I find using my thermal.
You can do this with an IR laser, but not as easy. If you do not want to hang a laser on your rifle, you can temporarily add one. I have an old laser laying around that I will slap on whatever for the task.
I started doing this to "rough" zero, but find it is as accurate as shooting hand warmers and such by day, probably more. It can be a pain getting a target on some days small enough for a fine sight in.