>o people publish as first authors during let say senior year? Like do I need to start reading ml theory and stuff now? I’m still taking calculus 1 as a fre

They get guidance. The question is not if you can write a paper as a BSC or not, it is whether your knowledge/commitment is worthy of some senior researchers time to guide you on how to navigate research/literature.

To publish you need an idea. Ideas are not created from vacuum. You need to develop it, or find someone who already has one. It simply takes time. Read a lot, understand what you read, and think how you can make it better.

They asked a senior professor in ML to do a summer project, and that professor gave them the idea and handheld them through it.

There are some people who have published as first author in their bachelors. From what I've seen, they are extremely talented and/or with good connection to some key people in the field.

However, their work usually shows a clear lack in awareness of the research that has already been done on the problem that they are now working on. It is kind of obvious, but this is something that could slip through the cracks.