Social Media Marketing While in Development

I am a week away from starting development and need to start marketing my venture. What I do not want to do is expose my idea so early on. What did you do to market your venture while in the early stages of development that was cost effective and protects your IP. What tools did you use to automate processes or cut down on costs? Is there an AI video or imagine creator you would suggest that I use? Did you use something specific to edit videos? What social media platform did you find provided you with the most interactions from actual users? Thanks!