If you believe the two checks reflect an attempt to structure the transaction in an effort to avoid the filing of a CTR, then you have 30 days in which to file a SAR. The time frame for filing a SAR begins when with the "initial detection" of the reportable activity without regard to when the activity actually took place.
The passage of time since the suspicious activity occurred does not eliminate a SAR filing responsibility. Moreover, a conscious decision not to file an otherwise required SAR is a crime, not just a violation of law.
In this world you must be oh so smart or oh so pleasant. Well, for years I was smart. I recommend pleasant.