I'd see how they behave first as I always end up with "nicknames" even though my cats have names. Things that "happen" with them and stick help me. My one cat I had 25-30 years ago, I wanted to name him "Rupert" but my DH and I and he were all walking and my DH claimed I'd named him "Rufus" so, Rufus he stayed!

My male cat now, "Calvin Klein" was named by the vet's office techs. They named the entire family after famous designers; I could have chosen "Ralph" but. . . LOL But I ended up keeping the name because I live in Maryland and I got him the same week Cal Rypken of the Baltimore Orioles retired. That helps me remember how old he was.

My female cat I named after my great grandmother whose life/self I admired (she died 10 years before I was born so I never actually knew her).

If you catch yourself calling them by affectionate little names, you could use the initials for their "actual" name; SP being "sweet pea" or "sweety pie" or whatever. "Hay" might be a nice name, short for "Hey You!"