The daily stipend of Robux arrives once every 24 hours. If you are in Builders Club, you will get your daily Robux whether you log in or not.
You can check and see that you received your Robux today by going to the Summary tab of your Trade section.
Note: The Past Day is what you got today. Past Week is the past week. Past Month is the past 30 days. Past Year is all of the Robux you have received over the past 365 days.