Will Depo Shot Shorten My Current Cycle?

Today is the first day of my period for this month as well as the first day I got on my birth control (depo).
My question is: Since I am just starting my birth control do I have to go through this cycle normally, as in bleed for the remainder of the 5 days or will the depo shot immediately decrease/stop my blood flow for the next 5 days until its time to take another shot? 
Reason: Valentines Day.. and I rather not be menstrating. 😑❣🖍📍