Incoming students are expected to begin no later than September 16 (which is when your funding begins), although Autumn Quarter doesn't begin until September 30. This will give you time to look around the labs and meet faculty and students. Other than attending scheduled orientation activities, there is nothing you are required to do during this time other than meet with faculty (to discuss potential lab rotations) and grads and generally get a feel for the department. Most students will arrive earlier in the month to look for housing and acclimate to Seattle. Please note that the 2020 department retreat runs Sept 23-25 and will be held online.
The UW will want proof of required vaccinations before allowing you to register. Please check the Immunization Website for more details. Please do not let this linger. It's a hassle, but putting this off can (and all too often does) cause registration delays and turn a small hassle into a much larger one.
Updated 7/15: Graduate Program manager Brian Giebel will contact you to arrange a zoom meeting sometime during the first two weeks of September to go over program requirements.
Employment paperwork is done online these days. The GS HR manager will contact you sometime in August / September to get this started.
International students will need to check in with the UW International Students and Scholars office. This can now be done online: http://iss.washington.edu/stu/ns.html . The UW graduate school has just set up an information page for admitted international students that you will surely find useful.
The UW currently waives the non-resident tuition differential for out of state students. While this has been a long standing policy, there is no guarantee that this will always be the case. In order to protect yourself and the dept from some future bit of fiscal madness coming out of Olympia, US citizens and permanent residents should take steps to establish Washington state residency, including obtaining a Washington driver's license or state ID, upon arrival. You will formally apply for Washington residency during your second year in the program (international students do not need to bother with this, since the UW will not grant residency to international students). Please note that this will be particularly important if you end up choosing to do your thesis research in a lab based at the Fred Hutchinson Cancer Research Center, since tuition payments are processed differently than at the UW and FHCRC does not automatically receive the non-resident tuition differential waiver.
This one is worth repeating: you will need to establish Washington state residency during your second year in the program. Please be sure to obtain a Washington driver's license or state ID shortly after arrival. It's a hassle. It is way more of a hassle to have to scramble to do this later on.