Hi project owner. I'm interested in your project. Please don't close this contest before the deadline you've set. I will submit my design for your project within the next 1x24 hours at the latest. Thank you.
Regards.

I'm not sure how to do that.

Hi, project owner.
Thank you for your feedback. You just need to let this project run until the deadline for submissions is closed and move on to the decision stage.
Regards.