I see that for international ratings they are updated once per month using all results from completed tournaments in that month. When are USCF updated and published?
Official USCF ratings are updated once per month. From the USCF's web site, this text appears in every player's rating record online:
The ratings shown on this page are official published ratings, which US Chess issues 12 times a year. As of September 1, 2013, Official ratings lists are generated on the 3rd Wednesday of each month and become official on the 1st day of the next month.
Unofficial rating updates are calculated quickly after an organizer submits a rating report for a tournament, and are usually available to view within a few hours of when the rating report is submitted. But these unofficial rating updates are exactly that - they're unofficial, they're not used for pairings or determining things like what section you can be in in a tournament, and they're subject to change and re-rating - most commonly, because the rating reports for events that a player participated in were submitted out of order. So, if a player plays in an event, the rating report is submitted, and within a few hours an unofficial estimated post-event rating is published. If then, a few days later, a rating report is submitted for another tournament that the player had participated in, that actually ended prior to when the first rating report was submitted, the player's post-event rating estimate for the other event (the one that the first rating report was submitted for) will be recalculated. But, as stated, these are just estimates, and they're not official in any way - they don't become official until the first day of the following month - and any changes that take place due to events that happen between the time the official ratings are calculated on the 3rd Wednesday of the month, and the first day of the following month, don't become official until the first day of the month after that.