The exercises that you'll have to submit for exam admission will start at some point in the next days and will be uploaded in the student portal (you should get an e-mail when this happens). Usually there will be one week to submit the solutions until the end of sunday in the following week, thus for the first exercise sheet you will have time until the 8th of May 2022, 23:59.
Other than that, there will be another poll to find out the optimal dates/times and the preferred format for the exercise sessions which will then start either next week or the week after. If there are some questions regarding the submission exercises (especially if you think there is a bug), you may of course ask them here too.