Depends how you look at things.
When I first started(and failed horrifically, long boring story), it was with a wood Duncan Imperial, white with gold graphics. Christmas 1978. Didn’t last past April. Didn’t break, was taken away when the string wore out after multiple repairs to end and never once doing a successful throw or graphic pull or sleeper.
Jump back to 2011 when I started to go after this “for reals”. I bought a Duncan Reflex and Imperial. I used the Reflex first, so I guess that makes it my first. The objective was to either pass or fail for cheap, and with 2 yoyos under $20(under $15 really), it was a safe bet either way. Obviously, I did in fact decide this was for me.
But, if we mean first “modern yoyo”, then that would be the DM2 I ordered a couple of weeks later.