Generating a delayed pulse with one 555 timer upon powering up the circuit

I created the following circuit that seems to be able to accomplish that task with just one 555 and no external triggers.

Explanation of my circuit:

• The left-side attempts to simulate a delayed trigger pulse.
  • R1-C1 is slowly decreasing the voltage from high to low and manipulates the length of time when output will be on LOW (~15 seconds)
  • R3-C3 is increasing the voltage but slightly slower than R1-C1 so that Trigger voltage dips below 3V but not for long
• The right-side is a monostable 555 implementation
  • R4-C4 manipulates the length of time when the output would be on HIGH (~5 seconds)

^{simulate this circuit – Schematic created using CircuitLab}

Here are the voltage measurements:

Here are the current measurements:

I think this implementation works but is there an easier way to accomplish that?