There is a few ways to tell. You can go to radioshack and buy a pocket magnifier with led light for 14.99. You look at the trichomes aka crystals and you want the heads to be milky/ a little amber. The more amber the less potent as it means past harvest. You can sorta but don't recommend this go by the pistols which are the orange hairs. If they turn from white to orange and mostly orange then that us also an indicator. Based on the picture I wouldn't harvest
I don't know your light setup but those buds seem very small. That could be not a lot of light/ nutrients. The colas just seem pretty small for harvest. it could be your setup though. If your wondering most the hairs are orange in the pics but that way is not the best way to tell. I don't want you harvesting to early.
Even though you are color blind you will still be able to tell the difference in shading of the triches under a scope. It's worth the effort.