I usually plant my hardneck garlic in the last week of February, and it's usually ready by the middle of July.
Due mainly to the weather, I was 2 weeks late planting them this year, although it looks as if they still may be ready by the middle of July.
A clue is the production of scapes - my bulbs are usually ready about a fortnight after these have appeared (and been snipped off and eaten!)
That tip doesn't apply to softneck varieties though, almost none of which ever produce scapes.
The OP's garlic still looks very green and therefore not ready for harvesting - although garlic foliage doesn't turn brown and tend to collapse in the way that onion and shallot foliage does, by the time the foliage is looking a bit brown and generally knackered, you can safely assume the bulbs won't significantly increase in size so can be lifted, dried and stored (if you leave them too long the individual cloves could start sprouting - disaster!)