No, messages are visible as soon as you post them. Occasionally moderators may move posts that violate Forum rules out of sight, but that happens pretty rarely.
You can see a list of your prior postings by going to your Profile page. Either click on your User Name on any posting you made or on the Profile button at the top of the page, then click on Summary and Show Posts.
Once you find the post you're looking for, click on the boldface Subject to go to the message thread where you posted it.