If you are trying to lose weight, you should weigh yourself once a week. Make it consistent by weighing in on the same day of each week and time of day if possible. You pick the day you want to weigh in. Posting that weight makes you accountable so be sure to post it. We won't judge!
If you are at a point of just maintaining your weight, it is a good idea to weigh yourself more often but you need not post it more than once a week.