The indicia of issue #19 lists Special Edition Publishing Company as the publisher.
The (Summer) 1974 DynaPubs Catalog lists:
#'s 1 - 16 as "NOW AVAILABLE"
#'s 17 - 20 as "AVAILABLE 7-15-74"
#'s 21 - 24 as "AVAILABLE 9-15-74"
#'s 25 - 28 as "AVAILABLE 11-15-74"
#'s 29 - 32 as "AVAILABLE 1-15-75"
This would extrapolate backwards to:
#'s 13 - 16 as "AVAILABLE 5-15-74"
#'s 9 - 12 as "AVAILABLE 3-15-74"
#'s 5 - 8 as "AVAILABLE 1-15-74"
#'s 1 - 4 as "AVAILABLE 11-15-73"
This agrees precisely with the "November 1973" date given in Flashback #1. It is also supported by the fact that the inside back cover of #5 lists issues up through #8 as being available. Likewise, the i.b.c. of #9 lists issues up to #12 available. To further support these dates, the DynaPubs (Summer) 1975 catalog listed them all as being available.