I think the bid is the most important factor. You need to see in your ad assets if all of the assets are served homogenously by sorting it on spent. Once you have find that out only then you'd know what the Blackbox named Google Ads is doing with your ads. Since my clients are generally miser so there isn't any pre-launch strategy. But I would recommend you to get in contact with your account manager and ask him to enrol you in the video only app ads which are in beta testing (last time I checked). These beta ads have highest engagement rate and therefore would be best for pre launch kind of arrangements.