Half Marathon Pacing Strategy

Hello! I’m currently about 3 weeks out from my half marathon, I was originally running this one just for fun but my paces have been improving with lower efforts/heart rates, so I’ve decided to lean into it and try and shoot for a PR. This will be my 3rd half marathon, so I feel like I have a good understanding of the race structure and at what points I need to fuel to avoid fatigue, but I’m not sure at what point I should be running at my goal pace. Any tips would be very much appreciated!!