So which is it gentlemen? 1 or 2 foot rise to get the concrete wet, or cement down to water level? Can't have it both ways.
And which expert thinks the ramp will be open on May 1st? That's 13 days from now. The concrete may be cured by then, but that's all.
At most, the lake will have come up 8-12 inches by May 1st. It's still dropping right now, and except for 2 warm days Monday and Tuesday, it's going to be cool and windy for most of the rest of the month. Not conditions conducive for a big pick-up in the runoff.
You can't launch most boats until you have at least 2-3 feet of water to cover the drop-off at the end of the concrete, much less the keep your motor from eating the dirt from the cofferdam.