The date of original issue is undoubtedly 1969 but what it was called initially (get it?) is anyone's guess. This may be the first stab by Topps, with no date shown on the box bottom as it was probably not a final proof:
The story is that Love Letters became Love Initials, in the packs at least, in 1969 and before allegedly being reissued as Mod Initials in 1972. Topps did that sometimes, marketing a set with a slightly differing box and wax wrapper a couple of years after its first appearance. I assume the "letters" were thought by the brass to be confusing, hence the change to "initials" but who knows?
Here's a Love Initials wrapper:
1969 on that code.
A ten cent box exists with (I am advised) a commodity number of 0-489-87-01-9 so the 10 cent wrapper above matches the box below.

As for Mod Initials, they had a test pack at a minimum:

All the Love/Mod packaging indicates Topps as being in Duryea, so they date to no earlier than the latter part of 1969. What I'm thinking is Mod Initials was the test and Love Initials the retail product and the 1972 dating for the former is incorrect. But I dunno.....