You really should invest in a test kit, monitoring your water is very important. You can take a sample to your LFS
and ask them to test it for you, however it will be hard to tell where you are in the cycle without regular tests (every couple of days at least) How much live rock or dry rock you have in there may help determine how long the cycle will take but it's usually between 4-6 weeks. Tell us more about the set up - filtration, lighting? What are your plans for this tank, fish only or reef?