Agreed; I take it you're speaking about your US (FBI) PCC. If you're currently living in the US, that PCC needs to be less than 6-months old at the time you submit your electronic application for permanent residency.
If you are required to submit any other PCCs (from other countries that you've been in, cumulatively for 6 months, since you were 18-years-old), they only need to be dated as at the last date you were in that country (so, for example, if you were last in Barbados on September 4, 2015, the PCC needs to have been issued on September 5, 2015)