First grow - how many weeks to harvest are my plants? Need to buy plane tickets

Here are pictures of my plants: http://imgur.com/a/IvSpC

Plants are currently in week 7 of flower after 3 week veg, growing indoors in a small tent in coco.

I need to buy plane tickets home for the second week of July but I don't know how long until they will need harvesting - and they are all different strains (white buffalo, gorilla glue, double dream) so not sure if they'll need harvesting at different times.

Can y'all tell from the pics when I should be trying to harvest them? I'm most interested in having the strongest active high so don't want to harvest them too late which I've read can lean toward more of a body high, but also don't want to harvest too early before they've reached max potency. Thanks in advance!