If you plan to take the RHCSA 6 or RHCE 6 exams, you’ve got to hurry because these exams will be withdrawn in two to three weeks.
As RHCSA 7 is not too different from RHCSA 6, it will not be too painful if you miss the date.
It’s going to be an other song if you wanted to take the RHCE 6 exam, because the v7 is an other world: you will have to start almost from scratch! Firstly, it’s now 3.5 hours instead of 2. Secondly, topics are different: network (teaming, bonding, ipv6, etc), Kerberos (NFS+Samba), security (firewalld), storage (iSCSI), and database (MariaDB).
If you thought about taking the RHCE 6 exam, book it now and work hard to pass it at the first attempt!