In February this year they declared that the "latency problem" was a "non-issue" and "never as bad as feared".
Additionally, problems with jitter had been solved and what little latency was there had been reduced further.
F-35 Test Pilots Will Begin Flying ?Gen? Helmet Display | Aviation International News
The helmet system’s latency, or response time at importing DAS imagery–measured in milliseconds–was not the problem testers thought it would be, Kelly said. Pilots just hadn’t had the opportunity to use the DAS sensor array during flight testing. “Initially there was concern about the latency of the DAS and what that might look like,” he said. “But we were able to do some testing in the spring and summer of 2013 where we looked at a bunch of different tasks [and] some formation flying and, across-the-board, we found there was really no issue with the latency.”
And in July this year the helmet was declared ready for service.
?Magic Helmet? for F-35 ready for delivery | Ars Technica