Is OK to post a challenge for a sandbox post with 0 votes but is 1 week old?
I have a lot of sandbox posts with 0 votes that are posted to Main, But this is OK?
The reason score/time are recommended (e.g. wait a week, have a positive score etc.) is because these are usually good ways of measuring if your challenge idea will do well. For example, a negatively scored Sandbox post is unlikely to do well posted on main, and a challenge left in the Sandbox for an hour won't get the feedback it might need.
But, these are recommended, not hard limits. People who are experienced challenge writers will often skip the Sandbox, or leave an idea for only a couple of days to get feedback, often in the form "Will this be a good idea?", because they're experienced enough to iron out any kinks in the spec by themselves.
Ultimately, you should post a challenge from the Sandbox once it is ready to be posted. If you aren't entirely sure if a challenge is ready, ask people in chat - often a "Any last feedback on this challenge?" message will get a response or two saying if it looks good to post, or if it needs more feedback.