Last year was my first, too. It can be very very exciting to say the least. You want your harvest to be as good as possible, no one ever wants to lose anything. What strains do you have dire? If they are mold resistant you will usually be A-Ok. Just shake the colas, especially last 2 weeks. September is a very rainy month, always is. I'm expecting mine to be ready to harvest by the 29th. So for me, I should stop feeding nutes some where around 15-19th aprox. That's just an example, mine are slowly getting some red on the pistils. My NL is pretty. Strong strain, while the Swiss Cheese is not very exciting, I think.
Last year harvest time was very exciting, at times I was a little uneasy about it all. But now that I have a year under my belt, its just not as exciting like the very first time. Although, I do believe every year will be different.