Oddly enough, or perhaps not, Mom and Dad suit. We feel comfortable with those nicknames. The kids asked us not long ago if we have always called each other that. Almost. We picked up the habit shortly after we were married and a few years before we had kids. We were still kids ourselves then, so we didn't use it a lot or exclusively, but we certainly used those appellations at times. They always felt right to us.
But times change. Around the middle of next April you can start calling me Grampa. What the heck, you can start now if you wish. But only if you really want to.
This, the first ever picture of my grandchild, I guess), is almost a month old. Read about the one who has been called Smudge at In The Family Way. Because it was taken ago, so I'm sure that a second portrait will soon be forthcoming. If memory serves, the little embryo, which is now officially a fetus btw, was only about 7 millimetres long but has now grown to a gigantic 1.5 inches or more.