If you give it before, it may be seen as shilling. It's best to post the thread and then invite reviewers
You can very well send a review copy of youur product. only remember that your product does not fall in category of spammy mentioned here.. http://forums.digitalpoint.com/faq.php?faq=rules#faq_rules_general
If you want to give away copies, you have to post it in freebies, and you may not exchange iTrader on them.