Hey,
Bounce rates do not directly affect quality scores, and neither do unhappy visitors. As long as your site is okay in terms of policy, you don’t have to worry.
On the other hand, I understand that your campaigns will produce a loss which is thought of as an investment in a good history to improve quality scores for later use – I’d advise against that. You don’t know whether the history will really improve your quality scores compared to the scores that Google would use without a history. Only if you are able to exceed Google’s expectations this will help.
If you are willing to spend money to get the campaign running, I’d say do that when you start for real. Instead of spending money now without generating any conversions to speak of, just save it and use it to bid higher when you really start. In case there is really a quality score disadvantage it would be offset by the higher bids.
HTH
Martin