I don't know. I emailed asking about their visit weekends and they told me the dates and that "invitations will be sent to admitted students within the next week or two." That was about two weeks ago.
MIT is holding chemE recruitment weekends on March 6-7 and March 20-21. You can always email the other schools to ask. The schools I applied to were pretty open about their dates before they sent out decisions.
I had an online video interview but have not heard back yet. Based on the email I got originally, it sounded like they were interviewing all top candidates for the program.