Well, you are a fairly early
Jaslyn, but as the creation of new names using the suffix -lyn was well established in English speaking countries long before 1974, you are unlikely to be the first.
After some Googling, I found a site devoted to an American rock band who tragically died in an auto crash in 1973, and one of them was a woman called
Jaslyn Walker. So even if she was not born with that name but was only using it as a stage name, it was chosen before 1974:
http://www.novemsongs.com/bios/jaslynwalker.shtml
Ancestry.com also has a birth record for a "
Jaslyn Elsie Jodean
Hudson" born in Columbus County, North
Carolina, on 30 Dec 1945.