One thing to add to what has been said above........

If you set your linkages up properly, with the servos centered, the surfaces themselves centered and the trims on your Tx centered, hopefully the in-flight trim adjustments will be minimal. If I have to make significant trim adjustment in the air, I usually readjust my control surfaces so that they are at their trimmed position with the Tx trim settings near neutral. This will require noting the relative position of the surface, neutralizing the trim control and then adjusting the clevis to put the surface back at it's noted relative position where it needs to be for straight and level flight. It's not absolutely necessary, but I prefer to have my trim settings within a few clicks of neutral with the plane properly trimmed. If you're way out near the end of the trim adjustment you're probably better off making the mechanical adjusment and then flying the plane again to finalize your trim settings. I think it's a good habit to get into.

Good luck with your plane.