Please reassure me: is there a waiting period for final IBR/IDR recertification payment amounts?

The other day I got a letter from Mohela with my new IDR payment plan (I signed up for IBR as it was the lowest payment amount recommended by the Department of Education repayment calculator of around $300) and the payment of nearly $600 begins in July with May and June being my old payment amount of $110. I was giving a forbearance for April’s payment.

But I also got another letter from Mohela a couple minutes later saying there is a 90 business day wait for a “Correspondence Processing Delay.”

Does this mean they’re still processing my recertification and having given me three months of low/no payment or am I going to be stuck with the $600 a month payment? Which was even more than the DoE repayment calculator gave for standard repayment. For reference I earn about $44000 annually.