You can write your acknowledgement either before or after the project. Generally, it is better to write your acknowledgement after the project is finished, as it can help you reflect on what you have achieved and thank the people who helped you.
If you choose to write your acknowledgment before the project, it’s important to thank the people who will help you to complete the project. Also, if you're clear about the things that you're thankful for, it’s easier to keep motivated during the project.
It’s also worth considering the length of your acknowledgement. If you’re writing a long report or thesis, you may want to include it towards the end so that it doesn’t disrupt your main text.
Ultimately, the choice of whether to write your acknowledgement before or after your project is up to you. It’s a personal matter that depends on your own preferences. Helpful steps for writing an acknowledgement can be found in this guide:
https://www.scribbr.com/research-process/acknowledgement/