It seems sensible to find the disc as early as possible. However, I think first I need to make sure I'm matching the receiver stride for stride, so I let them do the work of finding the disc early on and use that time to make up some ground.
Any work they do finding the disc will also help me pinpoint where to look for it. Once I'm matching their stride, I'll look for the disc and start making judgments about how the contest is going to pan out
If it's a leading pass, I just need to put my head down and try to get between the receiver and the disc, as close to the receiver as possible, and preferably with a decent jump. If I can establish a better line than them, I'll try to do that. Realistically, my high layouts are pretty ineffectual and injury-creating, but I've seen some great high blocks from layouts, so go for it if it's your thing.
If it's a floating pass, I would usually approach the bid from behind the receiver. If the receiver needs to back up, I probably try to establish position early to stop them backing up (but beware other receivers coming in for scraps!). If the receiver has good position, I try to stay out and get in a well-timed maximal jump at speed while they're standing flat-footed under the disc. If the cut is from the break side, it generally means there's a bit more room for negotiating position, so it pays to find the disc early and establish the best line at the disc.
If they have a height advantage, I'll try to establish position early and stop them getting a play on the disc. If I have a height advantage, I'll try to just find the place where I can bid for it at close to maximum jump and bid for it there, assuming they can't bid in the same place. But I want to minimise the risk of it going over my head and giving them a cheap win, so I include a bit of a margin of error in choosing that spot. So it helps to know if someone is short with big hops.
If it's a leading pass and they have a speed advantage, as they spike it in my face I probably turn around and start abusing the marker for letting out a clean huck.