if you get enough fast growing stem plants they'll basically help prevent ammonia and nitrite spikes since they use them for food. I've done a couple fish in on 5 gallons and did 2 50% water changes a week for a couple months since I didn't have anything to test the water with at the time and they came through it just fine. just have to make sure you don't slack on the changes

 

You cant leave plants in there without an ammonia source, no. Put your fish in for the fish-in cycle, and add those plants! (Especially if theyre stem plants like anacharis, hornwort, ludwigia, watersprite...),as these kinds are great at sucking up ammonia while keeping the tank in balance enough to still cycle. Essentially, they help cycle the tank while keeping your fish at a safe ammonia level.

In a 10 gallon with plants, assuming you have a few stem and/or a decent amount of other plants, and two fish, I would check the ammonia/nitrite readings every 3-4 days. Check and make sure its not too near or at/above .5ppm, which with plants, it probably wont be.

If you have enough plants, it probably wont show any ammonia at all! If these begins to be the trend, check every 5 or so days on the ammonia and nitrites and do a poop suck from the tank to keep it pretty. Do however much you need to get it poop free and ok, but try not to take out more than 50% at once.

After about 2 weeks, begin to look for nitrites. If you can/want to, check for nitrates at that point, too.

My tanks like to cycle that quick, which is surprising. Enough plants help to kick-start a cycle and do some of the work for you, as well as take away some of the worry

Keep any new fish in QT, of course... And of course of course, keep the filter on No 100% water changes, add in new water thats been PRECONDITIONED as to not hurt the bacteria, and of course, dont wash out the filter. If you really feel the need, maybe to get gunk off it, do a water change and give the filter a gentle swish in the water change water (old water) to remove the cruds and not kill the good stuff.

 

If you've only got a couple fish for a 10 gallon, I'd go ahead and put them & the plants in and just get started. Just keep up on frequent water changes, as Tisia mentioned (like a 50% every 3 days, for example and do a gravel vac once a week too), don't overfeed, and the cycle will eventually happen. I think it'd be more stressful on the fish in a separate container while you cycled the 10 gal, because you will still have to keep that container free from toxins (water changes). In a smaller container, the amount of toxins the couple fish would produce would be more concentrated than if they were in the bigger 10 gal which would dilute the toxins more... make sense? Therefore, you'd end up doing very frequent, probably 100% changes in that small container, which would be stressful for them.

And if you don't have a water test kit, it would be a good idea if you are able to get one to occasionally check what's going on with the water as the cycle progresses.