Good advice from Shellie, Lebron and Callistra.
Cycling two tanks at once is inefficient. You can cycle both filters in the 20g. That way you can run the ammonia up to ~4.0ppm, heat ~82*, lot's of filter flow and aeration. When that tankl is cycled, the extra filter will be cycled. Put it in your 10g and the tank will be effectively cycled. Get it?
Nitrite is funny. Sometimes you don't read any; sometimes you can't get rid of it. Monitoring your nitrate will give you a view into the progress of your cycle.
Use this: [ame=http://www.amazon.com/API-Freshwater-Master-Test-Kit/dp/B000255NCI/ref=sr_1_1?ie=UTF8&qid=1354771118&sr=8-1&keywords=API+test]Amazon.com: API Freshwater Master Test Kit: Pet Supplies[/ame]
Sorry, the price just went up, but it's still a deal. (Put a pebble in the #2 nitrate bottle for better mixing.)
If you're' getting ammonia reduction after only a week, you're doing really well. It's not uncommon for it to take several weeks even with Safestart or equivalent. The few plants you have will make no difference.
Keep your nitrite (when you get it) <5.0 and your nitrite <40ppm to keep from stalling. When you get high nitrite, do a 50% wc and cut your ammonia dose in half.
When your system (tank/filter) can reduce ammonia from 2.0ppm to 0.0ppm in a day or so, two times in a row, you're cycled. (That's when you install the other cycled filter in the other tank.) Do a large water change to cut nitrite and add stock. Perform weekly 30% to 50% pwc’s from then on. Monitor closely for the first couple of months.