It’s good to know where you stand. I highly recommend getting body composition scales, as BMI can be a little problematic for some of us. That said, in the absence of better scales, BMI can get you started. I weigh daily, not because I need to obsessively know my weight, but because it’s a stay-on-track reminder for me. Generally, once per week will do just fine. Just to prove a point that I’m not obsessive, I recently was working overseas for a month and didn’t weigh in once. 🙂 Know yourself, though, you don’t want weighing in to turn into an issue related to eating disorders.
One more note on this calculator. Regrettably, it only has the option for male or female, and not non-binary or other genders. I have no ability to change this. Please choose the sex that most closely matches your biological situation as hormones now and sex at birth impact your body’s physical composition. This is why biological (at birth) women have a higher threshold for fat.