Rescheduling will only delay your application, matter of fact more delay from your end will delay in processing your application, BTW your application is not completed until they receive you fingerprint result which might take 2 weeks after your fingerprints are taken. After they receive fingerprint, your 90 days clock begins for EAD, suppose you are not granted TPS in that time frame you are still eligible for EAD, Also note EAD processing time is 30-90 days. And I doubt if you file your EAD by the end of this month without having your fingerprint taken they will even begin processing it, until they receive your fingerprint result. Good luck!