At this point in time, there is no clear notification regarding the same. A parents body has filed a PIL in the Supreme Court requesting for JEE Mains and NEET to be postponed further due to the increased cases. They have come up with 10 reasons as to why JEE Mains should be postponed. And IIT Delhi has already cancelled conducted JEE Advanced in Foreign Countries. And Parents body from Gujarat also filed a PIL requesting NEET and JEE Mains to be conducted as per schedule without any delay. Supreme Court is yet to pass an order on it. So until there is an official notification regarding this from either NTA or MHRD, we have to assume that JEE  will be conducted as scheduled from September 1st to 6th. There are 36 days more to go for the D day and anything might happen. If Supreme Court accepts the PIL, it might then ask MHRD and NTA to file in their petitions and then a call will be taken accordingly after all the pleadings are heard. So while it is still under hearing, we cannot say anything at this point in time. We have to wait to hear from either NTA or MHRD regarding the same. Until then the only wise thing to do would be to prepare for JEE as if it is going to happen from September 1st to 6th  and NEET for September 13th so that if the schedule doesn't change, you are not thrown off the guard.