Early in the movie, there is a scene in a briefing room where Bryant shows Deckard some videos (called "Incept Tapes" by the crew) containing information on the escaped replicants. Here is the information that was shown on screen while the videos were running:

	Replicant (M) Des: LEON NEXUS-6 N6MAC41717 Incept Date: 10 APRIL, 2017 Func: Combat/Loader (Nuc. Fiss) Phys: LEV. A Mental: LEV. C
Replicant (M) Des: BATTY (Roy) NEXUS-6 N6MAA10816 Incept Date: 8 JAN., 2016 Func: Combat, Colonization Defense Prog Phys: LEV. A Mental: LEV. A
	Replicant (F) Des: ZHORA NEXUS-6 N6FAB61216 Incept Date: 12 JUNE, 2016 Func: Retrained (9 Feb., 2018) Polit. homicide Phys: LEV. A Mental: LEV. B
Replicant (F) Des: PRIS NEXUS-6 N6FAB21416 Incept Date: 14 FEB., 2016 Func: Military/Leisure Phys: LEV. A Mental: LEV. B

Note: You'll notice Pris (the "basic pleasure model") has February 14 - (Valentine's Day) - as incept date...

Explanation of replicant information:

The serial number of every replicant is actually detailed identification data, containing a summary of that replicant's statistics.

For example, Leon's no. is N6MAC41717;

N6 = Nexus 6
M  = male
A  = physical level
C  = mental level
4  = month
17 = day
17 = year

Note: There is an error in Leon's details as the serial number decrypts to the wrong date.
Also, we are left to guess what happens for Reps created in months October to December - do they use two digits, or move on to A, B, C?

The information given in the briefing scene establishes certain interesting facts. For one, we learn that Nexus 6 replicants are divided into both mental and physical categories, apparently ranging from "A" (presumably more than average, perhaps even superhuman?) over "B" ("average") to "C" ("below average" - for a Nexus 6, anyway).