In IL, bowhunting time starts 1/2 hour before sunrise, bu tyou can be in as early as you want, provided that you do not have an arrow nocked on the string.

For a morning hunt, you can't get in too early. I try to get finished setting up and sitting quiet about 1/2 hour before shooting time opens. That's a whole hour before sunrise, but I've found that I see the most morning deer just as shooting time opens or just after.

By getting in this early, it doesn't matter so much if I jump one on the way in, because I still have time for the woods to forget I'm there after I'm all set up. Things have all settled down and the critters are doing their normal thing again by the time I can shoot.

Also, if you hunt public land, you can take advantage of the lazy idiots who come in after shooting time opens and disturb the deer from their regular early beds or travel routes. Going deep and getting there early can pay off when you have other hunters to mess things up for you.