Re: two questions...
So for the most part, coming down early is not going to really be a problem except for a few situations.
If you are scheduled to process in on the 4th, you are scheduled to process in on the 4th. This is "mass-process in day" and begins training week. If you are planning on coming super early on the 3rd to get housing, its not going to happen, seeing as hundreds of people will be processing in, so no one should get a unfair advantage. For those who cannot get to Sandusky on the 4th to process in correctly and need to stay the night on the 3rd, would need to check into housing Saturday evening, evening meaning after HR closes for the day. They aren't going to make any special exceptions for this weekend to process in early, seeing as no one is really "needed" for work until Monday.
During the operating season, however, the case differs, if you happen to arrive the day before your scheduled date, it is up to your department to decide if HR is allowed to process you in. Most likely, throughout the summer, staffing is needed, so I wouldn't expect a huge problem if you need to come a day early. Remember, calling your hiring manager or HR can get these questions easily straightened out so you don't have to worry.
The coming early and checking into housing thing is really a privilege for people who live far away and can't make it in time for HR on their process date. It really isn't a way to "get an early start" on housing. HR would prefer that complete processing in via their directions, which means going in order with all your forms, housing being the last stop, as by checking in early it makes it difficult for all the paperwork to get to the right place. So if you really can't feasibly get to HR by around 4 on your process in date, then perhaps coming a day early is what you need. But if you live close enough where getting to HR in the morning or afternoon wouldn't be a problem, it's best to just process in following the regular steps.
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