Say Thursday, hand it over Tuesday. After a few rounds of that, your word starts working like cash.

Delivering early a few times changes how people plan around you. Instead of building in a margin for your slippage, they start treating your dates as real, which means you get given things that matter and asked fewer questions. That standing is built out of small margins rather than heroics.

Quote a date you can beat rather than the one you hope to hit, then finish before it. Do this three or four times without drawing attention to it. The habit gets noticed precisely because so few people bother with it.