BIG BAITS or little baits
Your retrieve and location is more significant than bait size is. Opening day the past half a dozen years the smallest thing I've thrown has been the standard sized DDD. I start fishing as early as possible (midnight) and have at least doubled each year by 6am. Pounders, hardheads, large hellhounds, large DDD's, a home made copy of a suick that is 16 inches long have all produced and moved fish consistently very early in the season. It's not bait size, it's location and when everyone else is tossing the small stuff I'm chucking "fall" baits. I'll use the smaller stuff when more finesse is needed working around obstructions or when a window opens up towards the end of summer when a smaller bait is the ideal tool but early on regardless of where I'm at it's the big stuff.
I would also add that the reason why you hear about smaller baits producing there is because more smaller baits are being used than anything else. You'll catch 90% of your fish on a bait you use 90% of the time. Nothing magical about it, it's just a self fulfilling prophecy.
Been fishing Cedar for years with a bunch of guys out of Southern IL.
A number 5 or 6 Mepps bucktail should be adequate for your needs on Cedar in June. As the lake currently sits you'll be wanting to hit the weed edges in the back of bays, always good are any saddles, primary and secondary windblown points as well as any major rock outcroppings, mudlines or boulders providing a point of attack for Ol Esox.
Got to think small in June. Big baits might get you to move fish but our past experience shows that a smaller natural sized bait gets you hooked up.
Never can rule out a good topwater bite so a big poes cedar, big zara or even a chunky frog might be a good ticket!
Good Luck on Cedar!! You will be making plans to return year after year.