Have you ever host led an event week? I like the idea behind yours, but there are some things you should do first. One promote a couple of weeks in advance. Get people excited for and give them time to think of submissions for it.
Then you need a tag for people to search it by. It’s pretty simple to do, but vital for a good theme week.
Have some examples during the time you are promoting it. Your meme above is actually a good example of that, but as the host you will need more ready to go.
Lastly pick the dates. Events have a time set by the host. Check out Doggo week as a good example. Search the tag and look at how they went about setting it up. Good luck, it looks like it can be fun :)