Do not create or place ads if your site is under construction.

Google AdWords, one of the largest PPC engines, will eliminate your ad if your landing page is under construction. It will check that your landing page contains content relevant to your ad, so the landing page for your ad must be complete. If your site is under construction or down for maintenance, you can “pause” your campaign. Bringing web traffic to your site before its complete is not a good plan anyway. Who wants to buy from a company that looks sloppy and unprofessional? Take the time to plan out your design and your campaigns so you use your online advertising budget as effectively as possible!