Cut a slice out of the middle and fry it up - if cured it will be sorta bacony (no smoke) if not cured it will be more porky in the center of the strip, usually looks a bit different than the rest too while frying, kinda grey if not cured, pink if cured
what temp do you smoke at. One recipie says 240 for 2 hr then 180 for 2 hours then 200 for 2hrs. others say 100 degrees for 8-10 what works best for everybody
I cold smoke (100*or less) for 6-8 hours or until color is where you want it.
You don't need to get the internal temp up to safe levels unless you don't plan on frying/cooking it after smoking.
Allowing it to air dry in the fridge for 24 hours before smoking is a good idea too, helps the smoke stick better. I also recommend removing the skin (if its a pork belly with the skin still on) before smoking too. Other wise that will be a whole side that gets no smoke.