It isn't too late. The piano is the basis for other instruments because the keys are laid out. Music theory or learning the notes on paper and the piano becomes easier with practice. As my teacher said after about 3 and a half years of playing, it all becomes natural after a while, and he was right. Despite playing many notes at once and having two clefs to play with, the piano is generally easier in many ways than most other instruments.
For stringed instruments like a violin, you might have trouble even hitting the correct note in an exact place, and ones like the guitar, the same notes can be on different strings, so finger positions and moving your fingers up and down the guitar can be hard. And for any other instrument like a tuba, for example, the notes are not laid out, except for things like an organ or harpsichord.
When I first started piano, I practiced for about 3 hours a day, and now I do it for an hour. It's definitely important to practice longer and keep playing when you first start so you can continue to develop the musical experiences in your head. After about 6 and a half years I was playing some of Frederic Chopin's Easier works, and at 7 years I could play some of his more difficult works such as is his etudes also decently well. After 8 years of experience, I could finally play some of Chopin's technically demanding works very well, such as some of his etudes, polonaises, and one of his concertos.
I don't know how fast you will learn, but it is a common myth that you can't learn any faster when you're older. It's just a mentality thing, because younger people are not as exposed to what goes on in the real world, so they want to focus on their music. If you really have dedication to practice getting better and correcting wrong habits, you should learn pretty quickly. On average it takes people about 3 to 5 years to play intermediate level songs. It took me about 3 years. I am guessing it will take you 4 years because you do seem like you have a lot of responsibilities, yet you also seem very intelligent and motivated to learn music.
Standard pianos are 88 keys, and before you know it certain notes you play will need to be much higher or lower than middle C on the piano. So you can get a feel of the octaves, it will help to get a feel of where to put your fingers in certain places. Simply moving your hands up and down the keys and doing finger exercises can help with note memorization and musical understanding. I used to do this all the time after I practised certain pieces as a beginner. Lessons would also be good to avoid developing bad habits that can be extremely hard to break.
I wish you the best, and hope you do well starting the piano!
Maxwell
P.S.- I have always had lessons every Saturday, and the times have changed over the years. But I have stayed with the same teacher. He was born in Paris France in 1950 and was the only one in the world that had permission to record certain Sorabji piano music for publishing, which is very difficult.
It's good to practice what you have learned and try to correct habits yourself each day, and then finally learn more, instead of learning too much each day. My piano teacher didn't let me move onto other pieces most of the time unless I played the pieces at least decently well.