I agree with Vancouver. Let them go at least 8 weeks and you will have at least 2 jars of primo bud to smoke on. It's good to hear that you have more clones ready to go! Do a few grows and you can be smoking for quite a long time. They are looking great so far. Keep up the good work and you will be well rewarded.
You should definitely look into buying a scope to look at the trichs. The little ones from radio shack are 60-100X magnification and they work great. They are kind of small but I clip off a tiny piece of budleaf and sit it on my table and study it closely... Definitely the best way to determine when to harvest. Just my thoughts. Keep us posted on your progress. Take care and be safe.