Stone Cold a great rifle there.... due to your lack of time you are best off getting some 50 grain pellets and some powerbelts. Put two pellets in it only, and try some of the different size powerbelts. One of them should click into that rifle. Be sure and swab between shots.

After the season and you have some time, then you can look for sabot loads. Otherwise if you really want to shoot sabots, then get some T/C Shockwaves in 250 grain and shoot 2 pellets with them. It should give you good accuracy.

If your running loose powder the loads might tune in somewhere between 80-100 grains. I am only basing this on my CVA Staghorn. I so not have a Optima Pro.

Good luck