3V LED flash with SMD 2 pin header probe

*2 PCB designs total, both using all SMD parts* 3V LED flash with SMD 2 pin header, water activated. powered by 3v CR927 battery, this project will have 3 separate standard 0805 LEDs that flash in sequence. The LED's should be placed as close to the edge of the PCB as possible for use of right angle LED's with curved lens. This unit will be liquid/water activated. Example, when the probe touches a body of water it activates the circuit, then LED 1 turns on then off, LED 2 turns on then off, LED 3 turns on then off. and then the LED on/off sequence loops indefinitely until the probe exits the body of water. LED's with forward current of 2mA will be chosen, a 100mAh CR927 will be used for maximum battery life. PCB Design #1 - Battery below PCB - PCB should be as small as possible diameter no greater than 12.7mm PCB Design #2 - Battery on top of PCB - PCB should be as small as possible. Unknowns for project - (1) how fast to flash the LEDs Thanks, this will be fun!