There should be a grace period. Do not waste time to rescind. File an order to show cause. See an adoption attorney right away.
973-984-0800. Please be advised my answers to questions does not constitute legal advice and you should not rely on it, due to the fact that we have never met, I have not been aprised of the facts in you case nor have I reviewed any documents.
First, if you signed NY documents NY law applies. You need the assistance of a good adoption attorney in NY. Having a grace period dies not mean you will automatically get the baby back.
Second, if you signed NJ forms in NY, you should have also signed a Choice of Law Statement.
My bigger concern is why the change of heart at this time. Did you genuinely change your mind or is something else going on? Depression and post parting depression, which is normal could be the cause. Also, too many people put guilt on birth mothers, because they don't understand the circumstances. Did you have counseling? If the agency is good, they would have offered counseling. I highly recommend you contact the agency and discuss your feelings. Most agencies are very good.
Good luck. Birth mothers are very strong ladies who put their feelings and second, because the are motivated by what is in the best interest of their children. I have been practicing adoption law for 29 years and I am always amazed how unselfish birth mothers are