Buy a test kit. You'll have a hard time monitoring your tank without it unless the LFS is 2 minutes walking distance away. My nutrafin test kit states the following:
Ammonia: if above 1.2mg, do a 20% wc;
Nitrites: if above 0.3mg, do a 20% wc;
Nitrates: if above 50mg do a 20% wc;
Now I never had a problem with Nitrates but I'll tell you that during the time my tank was cycling, I would do a 20% wc pretty much every day, for a 2 week period. AT some point it peaked and simply died down, and that's when I knew my tank was cycled. Now I was adamant about doing a daily wc because I was cycling with fish as you are. Your cycle will likely take longer to start and complete because you only have 3 small fish in there... it's all about having patience! I don't have any!
The more fish you add, the more maintenance you will have to be ready to do during the cycling process. Once that's done... maintenance is a breeze.
Oh and welcome to the forum eh? (Yes I'm Canadian