Is it normal for the mixer to show up way before the scheduled pour time?

The 6:30 arrival is a standard move to ensure you are the first pour of the day. If you aren't the first truck out of the gate at the batch plant, you're at the mercy of every other job site in the city. One delay at a different site means your '7:00 AM' truck doesn't show up until 11:00 AM, and by then the sun is baking your subgrade. Your contractor wants that truck sitting there ready to go the second the clock hits 7:00 so the crew can finish the hardest work before the heat index spikes. Concrete is a chemical reaction, not just mud drying. When it's 85 degrees by noon, the surface will 'crust' or flash-set while the bottom is still wet, wich leads to spiderweb cracking or a terrible finish. Starting at dawn gives the finishers a window of cooler air to get the cream to the surface and get it smooth. If the truck shows up and your forms aren't tight or the rebar is sagging, you're going to pay **standby fees**. Usually, you get 30 to 60 minutes free, but after that, they charge by the minute. It’s not unheard of to see $150 an hour just for the truck to sit there idling. As for the HOA and the neighbors, the driver will likely keep the drum spinning at a low RPM to keep the mix from setting, which isn't whisper-quiet but isn't as loud as a full-speed discharge. Most drivers are used to 'hiding' around the corner until the exact minute the permit allows them to pull onto the property. If you're really worried, just tell the contractor the truck needs to wait at the entrance of the neighborhood until 6:55.

Don't be surprised if the driver is actually early and your contractor is still frantic. There’s an unwritten rule in the industry: if you’re 100% ready, the truck will be an hour late; if you’re still hammering stakes, the truck will be five minutes early. Just make sure your subgrade is damp before they pour—dry dirt sucks the moisture out of the mix and ruins the cure.

Listen to the kid, he’s right about the timing. Back in my day, we’d have the lights out and the string lines tight by 5:00 AM just to beat the summer humidity. If you're lucky, your driver is an old pro who knows how to 'creep' the drum so the neighbors don't get thier feathers ruffled. I once saw a guy try to start a driveway pour at 10:00 AM in July—ended up with a slab that looked like the surface of the moon beacuse the mix got 'hot' in the drum. Your contractor is doing you a favor. Just make sure you’ve got a box of donuts for the crew; a happy finisher works alot faster when the sun starts biting.

I'm still trying to wrap my head around the 'standby fees' thing. If the driver shows up at 6:30 but the permit says we can't start until 7:00, am I basially paying for those 30 minutes of idle time? That seems crazy if the contractor is the one who scheduled it that early. Also, what exactly do you mean by 'dampening the subgrade'? Do I just spray it with a garden hose right before they pull in, or is there a specific amount of water it needs so it doesn't get muddy?

Regarding your subgrade inquiry, the objective is to achieve a state of 'saturated surface dry' where the soil is sufficiently hydrated to prevent it from thieving moisture from your mix via capillary action, yet lacks standing puddles wich would locally increase the water-cement ratio and inevitably compromise the structural integrity of the slab. I would personally advise using a fine misting nozzle to achieve a uniform dampness rather than a heavy-handed drenching, as the latter often results in soft spots that can lead to differential settlement under the considerable weight of the wet concrete. While the standby fees are indeed a point of contention, the cost of a failed pour due to inadequate moisture management or a late-morning flash set is exponentially more taxing than thirty minutes of idling time.