I was going to let more experienced people answer, but since you aren't getting a lot of answers here, I'll add my two cents. Which, in reality, is actually someone else's two cents.
One of the very experienced and knowledgeable members on this forum, TheHoneyPump, gave me some treatment guidelines that I have found very helpful, and perhaps they will be helpful for you too. He told me to check my mite counts by sugar roll or alcohol wash in the spring before the hives get built up, before you put supers on, when you take the supers off, and before winterizing, and of course any time you are seeing evidence of mites (viruses, bees pulling brood, actually seeing mites on the bees, etc.). He recommended if your mite testing comes up with 0-2 mites per 100 bees, you don't need to treat; 3-5 mites/100 bees use a soft/organic treatment if it's summer and a hard/chemical treatment if it's fall; and anytime of year, if you see 6+ mites/100 to treat with a hard/chemical treatment. Alcohol washes are more accurate, but I always do sugar rolls because I don't like killing bees if I don't have to. To help compensate for the inaccuracy of the sugar roll, you can multiply the number of mites by 1.3, to get a little more accurate number.
Here's how I do a sugar roll. I pick a frame from the brood nest that has a lot of bees and does NOT have the queen. I have this 2 gallon garden tub made of kind of bendy plastic and I hold the frame vertically (sideways) over the tub and give it a stiff shake to knock the bees into the tub. (I used to use a brush, and sometimes I still do if there aren't really enough bees on the frame.) I pour the bees from the tub into my sugar roll jar, which is a qt. mason jar with #8 hardware cloth in the lid ring. (It's weird how bees pour, but they do.) I usually roll 1 cup of bees which is about 600 bees. After I screw the lid on, I put about a tablespoon of powered sugar in through the mesh, just eyeballing the measurement with my hive tool. Then I put a plastic dish on top of the jar to keep the sugar in, and shake it up really good to coat the bees in sugar. Then I set the jar in the shade for about 5 minutes to let the bees get warm and "cook" the mites off. Then I turn the jar upside down and shake the powdered sugar onto a paper plate, and with the sugar comes any mites. I usually spritz the sugar on the plate with a spray bottle of water to dissolve it, so I can see the mites better. Be sure to shake out as much of the sugar as possible, or your numbers will be inaccurate. I return the (now very angry, but thankfully unable to fly) bees to the hive, being sure to check the bottom of the jar for any mites as well. Then just do the math to calculate the mite/bee percentages, and from there you can decide what treatment, if any, you think you may need.