Honestly, as a freshman I don't think you need to worry about this much. Do try to get into labs and make the most of it, but make sure you aren't absolutely focusing on grad school. Your goal should be to evaluate whether or not 1) you want to actually pursue psychology and 2) you want to study/focus on younger populations.
I went into uni knowing that I wanted to do psychology, but it still took me about two years before finally taking all the science courses outside of psych. Which meant I had a really weird undergrad transcript Still got into an excellent program.
Basically, my advice would be not to worry too much about doing things *right*, but rather on finding your own path and interests. Be part of a lab. Take classes that interest you outside of psych. And so on. Really cliche I know, but hey it's solid advice