Fields that should be useful
Previous sign-on century: UPPSOC A 1
Previous sign-on date: YY UPPSOD A 6
Note UPPSOD is A6. it contains a value like 090217
YYMMDD. So you need to compare it with 081217 (for 2 months or you could get fancy and go for 60 days)
not with 60 and you are looking for dates that are less than 081217.
UPPSOC should contain a 1 (through 2050) a 0 indicates 19′ but you probably don’t need that,until the year 2100.