I'm not OP, but I'll drop my two cents anyway. I initially started learning on a 76 key non-weighted keyboard. It was a good platform to start with but it very quickly became a limitation. Some of the pieces I wanted to learn were simply impossible, because the piano was a few keys short.

I moved to an 88 key electric piano within a month or two, and the difference was immense. It took me a while to get used to. I didn't have much control over my finger strength and I had to stretch them farther than I was used to.

In my experience, moving from the electric piano to upright/grand pianos wasn't as big a deal. If I'm playing on a new piano I'll play for a few minutes just to get a better feel for it anyway. My friend's grand piano feels different to the grand piano I practice with in college for example.

My advice would be that if you want the piano to last you more than a year, invest in an 88 key weighted keyboard. Personally I like electronic pianos because I can easily plug my headphones in and play late into the night, however I think stringed pianos sound/feel better.