The best test kit is the one left at the store, or if already purchased, the one dumped firmly in the bin. They are inaccurate and cause more problems than they solve most of the time. As Nathaniel said, let the tank mature for that period and then if you want you can take your water sample in to your LFS and they can test for ammonia and nitrrite. But with decent planting there is little chance it wont be matured in that timeframe.