I have 7 planted tanks, some heavily, some moderately, I normally do not have a nitrate reading in any of my tanks, all tanks have been set up with fish living for years. The blanket assumption your tank is not cycled unless you have a nitrate reading in a planted tank is misleading. Decaying plants will feed the bacteria, maybe not enough to prevent an ammonia spike if you add a lot of fish, but if you have plants in your tank, you probably do have some bacteria present. If you stock lightly at first, and do 50% water changes every few days while the bacteria builds, you should be fine. To be safe, I'd go spend 10$ on a bottle of Seachem Stability, I cycle all my new tanks with it.