I don't think Stability speeds up the cycle. I think it just renders Ammonia non-toxic to fish. Helps keep your fish from dying while the BB colony catches up. Personally, if it was me, I'd call it done. You get close to 0 ammonia, and 0 Nitrite, and you're measuring some Nitrates. That means you have bacteria turning Nitrite to Nitrate, since you were getting Nitrite readings previously. Just add fish slowly, make sure you use Prime when do a Water Change if you have chlorine or chloramine in your tap water. I have 2 tanks cycled for close to a year now, they never read exactly 0 Ammonia, they always read 0 Nitrite, and they always read at least 5-10 ppm Nitrate--and as high as 60-80 ppm Nitrate sometimes. I think you're good.