I'm gonna be a contrarian for a minute; hear me out: If this is your first GenCon, DON'T schedule yourself for ANY events!
1) I wasted the better part of 3 hours Thus. morning just by bribing a hotel valet parking attendant, waiting in the Will Call line for 1.5 - 2 hours, and then running back across the street to re-valet my car. (I had purchased a Gate 10 Parking "event" ticket, but I thought I couldn't park at Gate 10 until I first obtained my event ticket, and I couldn't obtain my event ticket until i waited in Will Call, and I couldn't wait in Will Call until I parked -- see the dilemma?) Thankfully, I did NOT schedule any events for Thurs. morning. A guy waiting in line in front of me, however, was supposed to compete in a World Qualifier for Yu-Gi-Oh!; he had to forfeit his match because the judges wouldn't let him participate unless he had a physical paper ticket -- which he couldn't obtain until he got to the Will Call desk. See the problem? (You could, of course, just get your badges and event tickets MAILED to you in advance, or wait in the Will Call line on Weds. evening instead.)
2) Although the wizards behind GenCon have a pretty decent computerized system for queueing you up to purchase Event tickets, including a way to make a "favorites"/"wish" list, and a way to ensure you won't accidentally "double up" if you and an authorized friend are both attempting to buy tickets to the exact same event at the same time (i.e., you aren't forced to unwillingly compete against each other); it seems the tickets to the uber-popular and limited-release Events go QUICKLY. Meaning: they completely sell out in in the first 5/10/20 minutes on the first day that they go on sale. So, plan accordingly; fill up your "wish list"; and be sure to prioritize/number your events in the desired order ahead of time, but don't get your hopes up too much.
3) The exhibition/vendor hall is HUGE. You could easily spend an entire day in there, wandering from table-to-table. Some of the vendors have waiting lines (Example: the fresh-off-Kickstarter "Kingdom Death" booth last year.) Each line will take up 10-20 minutes of your time. Many of the vendors also offer free demos throughout the day; no event tickets necessary! Some are 15/20 minute demos; some let you play the full game all the way through.
4) GenCon is CROWDED. We're talking morbidly-obese people, folks in motorized scooters, folks with walking sticks/canes, folks with kids, folks in bulky costumes, folks with large SWAG bags/backpacks, etc. Each of these people is gonna periodically stop and take a selfie. Each of these people is going to see a large group of people crowded around a booth or sweet cosplayer, and they'll temporarily add themselves to the ever-growing crowd. It takes time to navigate around all of these crowds.
5) GenCon itself is MASSIVE. It's spread out over several city blocks, including the Convention Center, Lucas Oil stadium, several hotels, and the streets and underground / overhead ("Habitrail") tunnels in-between. It takes time to get from A to B; even more time due to #3 above. You don't want the stress of trying to run from Event A (in one corner of the convention area) to Event B (in the opposite corner) in just 15 minutes; it ain't gonna happen! Plus, it's rude to force everyone else to sit around waiting for you to show up before the event can begin. Or, the GM will just start without you and give away your spot/slot to a Generic Ticket-holder.
6) You can get into plenty of events with "Generic" tickets. Even if your desired event is "sold out," you can still just show up on time with a "Generic" ticket in hand, and wait a few minutes to see if someone fails to appear.
7) There are plenty of other free things to do that don't actually require tickets. Examples: Cardhalla (observing the towers beforehand, but not knocking them down with coins); the Costume "parade" (which happens just prior to and/or immediately after the official Costume Contest); the Sun King beer tapping; people-watching; etc.
8) You're going to want plenty of "down time" to sit, rest, use the bathroom, eat and drink. Seating can be scarce.
My point is: for all of these above-mentioned reasons, it's quite possible that you could have a perfectly good time just wandering around with a badge only, and NO event tickets (or maybe just a handful of "generic" tickets, just in case)! I'm not saying that's what you *should* do; I'm just saying don't worry about it too much, and give yourself some wiggle room!