This type of issues is rooted in the bankruptcy rules. First, Rule 4002(a) creates a requirement that a debtor puts their property and their exemptions (claimed under section 522) in the applicable time limit stated in Rule 2001.
Rule 1007(c) states that a debtor in a voluntary case (the most common) is required to file a list of their exemptions within 15 days of the petition being filed (but your Chester County bankruptcy lawyer in an emergency filing may push the deadline back via Rule 1007(c)). This extension may be granted only on motion for cause shown on notice to the U.S. Trustee and with a host of other complicated rules. Trust your lawyer to get this done if necessary.
Bankruptcy Rule 1007(c) provides that a schedule of exemptions filed prior to the conversion of a case to another chapter (either 7 or 13) is deemed filed in the converted case unless the court directs otherwise. But, if your lawyer doesn't get the exemption, it will be interpreted as a waiver of exemptions (note: This never happens if your Chester County lawyer is halfway decent).