mongodb schema design naming convention

So I have something called

exports.create = function(projectJSON){
 
 var project = new ProjectModel({
   id : projectJSON.id,
   projectName : projectJSON.projectName ,
   authorName : projectJSON.authorName,
   firstPostDate : projectJSON.firstPostDate

 })
}

Is the above naming convention for a multi-word element firstPostDate (camel case) correct, or should they be spaced with _ in all lowercase?

I see that other blogs prefer it to be in small caps.

Also I read that elements should be singular instead of plural ie:

`comment` instead of `comments` for a blog schema design