D type flip flop to divide astable 555 by two
And this is why all sequential circuits need a reset!

Without any external aid, the state of a flip-flop on start up is a...coin flip, basically.  This is one reason most flip-flop ICs, and just about all larger sequential (flip-flop-containing) circuits, have a RESET or CLEAR pin.

Fortunately, power-on reset circuits are cheap (the MCP100 is a representative part in TO-92 that costs $0.34 in unit quantities at the time of this writing) and easy to use, as you simply need to hook up power and ground to the chip, and it provides an active-low reset pulse on power-on or a brown-out that can be fed to the RESET or CLEAR pin on your flip-flop chip. (Some other parts use an open drain output that needs a pull-up to the power supply.)