I was in your same boat bro, my nerves even caused me to fail my stage check IMO. In terms of controlling nerves I honestly think having to cancel all those times calmed them by making it anti climatic. Also once I got into the cockpit everything just kinda "clicked" and those nerves went away. Of course these are all personal anecdotes. As for tips, at this point the checkride is a mental game. You have the skills to become a private pilot, that's why your CFI signed you off, so the only obstacle is not letting yourself become your own enemy.

Take a proficiency flight before your checkride, I took mine the day before. It greatly boosted my confidence for the checkride.

Get good sleep, no brainer here the only issue is getting to sleep when you are nervous. Honestly I have no tips for going to sleep while nervous. The only reason why I was able to fall asleep was the fact I had to drive 7 hours for the checkride.

Go in with the mindset you will pass, everyone there including your dpe will have the same mindset. Don't go reading all these posts about checkride failures or nightmare dpes. There is nothing wrong with these posts but when you read them before a check ride, you condition your brain into expecting the same result.

Communicate with the DPE, even though you are PIC. Ask the order of landings, or whether or not to do clearing turns before certain manuvers. Do this for both the preflight and actual flight in case you forget. Keep the questions related to the flight.

Mistakes aren't the end of the world so long as you catch them right away. Literally in the ground I had 7500 feet for a course of 357. I noticed right as he asked me what altitude I picked and why. I explained to him my mistake and some things we could expect with 8500 and that was that.

Build rapport with your DPE, it turns out him and I both went to the same medical examiner. Be honest and say that you are nervous. If they are a good DPE they will try and help you iut with your nerves. For me all of these things made him feel more like a friend or a colleague rather than an examiner.

Recognize what you do when your nervous and fix them. For me I start to look inside when I'm nervous. Catch yourself doing this and fix it.

Get a gouge for the DPE- self explanatory.

Take everything one step at a time. For me I have to do this verbally. I mentioned to my DPE that I would probably think out loud and even though I'm sure it made me look like a weirdo. It helped me pace myself during manuvers. But basically just go slow.

Recognize wind and that you can always go around. If you have a headwind for a shortfield you will float less. Pretty obvious fact but it's something that myself and my friends forget causing us to undershoot. Do a go around if you don't feel comfortable with a landing they will not dock you on this. My last landing coming in the approach was fine but I felt off so I did a go around. I explained to him that I just had a bad gut feeling and that was that.

BELIEVE AND HAVE CONFIDENCE IN YOURSELF. This is definitely easier said than done espically for me as I struggle with imposter syndrome and self doubt, but at the end of the day, you have the capability to fly a plane.

Lastly, WATCH PPL MOCK ORAL VIDEOS. This probably helped me the most with ground knowledge. I recomened the ones from the "cheese pilot" channel.

As a quick side note I will say the whole entire exam was very underwhelming. I was expecting an SAT level ground and a line check flight, but i got a like 45 minute ground, and maybe a 1.2 hour flight. It honestly just felt like another ground and flight with my instructor.

You got this!