Before you even look at the water supply, dry-fit everything. Take all the pieces—the trap, the extensions, the tailpiece—and connect them without any glue or tape. This is your chance to see if your vertical tailpiece from the sink actually lines up with the wall pipe. If it’s off by half an inch, don’t panic. You’ll use a slip-joint extension (a telescoping pipe) to bridge the gap. They sell those at any hardware store for five bucks.
If the dry fit looks good, you get a tiny dopamine hit. If it wobbles, that’s normal. The adjustable nut will fix it later. The key here is to make sure the trap is level, not tilted. A tilted trap will leak every single time, usually at 3 AM when you’re sleeping.
