Form 1310 processing time

My father passed away late 2019 and I paper filed his return. Today a letter came in asking for a copy of one of his W2 forms that I forgot to include and to fill out form 1310 to claim his tax refund to pay off his credit card debt. My question is how long does it take the IRS to process the form and release the refund? Someone else told me it took all year and they ended up needing a taxpayer advocate to help.