Short version:
Just claim between 16 - 21 June, and claim again exactly 19 weeks later.
Long version:
You can claim anytime you like, even now.
The best time for first claim to potentially get the 100% reward is between 16th - 21st June. If you claim on the 14th June it is fine too but you forfeit the reward on the 15th June (final day of reward). One thing to factor is gas fee, if they are dead cheap on 14th then do your math.
After your first claim, you will be continuously rewarded with the unlocks until 5th Dec. You can do multiple claims or to safe time and fees claim once right before 5th Dec. Smart contract closes on 5th Dec so that is the last day anyone can claim.