This is determined by your campaign settings. We can set up your account to run at whatever hours of the day you wish. The only other factor influencing when you can see your ads will be your daily budget for the campaign. If you have a restricted campaign budget then your ads will be rotated throughout the day to ensure you do not exceed this. It is not best practice to use daily budgets to control your campaign, but in some instances where there is a restrictive budget, or you would rather appear higher, but less often, it might be the only solution.