Adjust timing in a rule (switch speaker one-by-one)

Hey All,
I use the following two rules to turn on my speakers (even with amazon ECHO (a dummy item))
This should give the amplifier a 4 second delay, before turning on the Subwoofer.
Or turning of the subwoofer 4 seconds prior the amplifier.

Since i added a script to check, if i controlled the switches from another site, i added rule two.
How can i avoid timing errors, which will lead really often to the circumstance, that “Port2_4” stays on (switches off, and then really quickly on again)
I would like to implement another condition in the second rule, to check if the 4-second-timer is active.
I created this rules to avoid an earthquake when shutting down subwoofer and amp together.

Thanks :+1:

rule "Audio Delay"
	Item Audio_ALL changed
	if(Audio_ALL.state==ON)		{
    if (audiodelay != null){ audiodelay.cancel()}
	sendCommand(Port2_4, ON)
    audiodelay = createTimer(now.plusSeconds(4)) [|sendCommand(Port1_2, ON)]}
	if(Audio_ALL.state==OFF)	{
    if (audiodelay != null){ audiodelay.cancel()}
	sendCommand(Port1_2, OFF)
    audiodelay = createTimer(now.plusSeconds(4)) [|sendCommand(Port2_4, OFF)]}

rule "Audio Update"
	Item Port1_2 changed or
	Item Port2_4 changed
    if (Port1_2.state==ON  &&  Port2_4.state==ON  &&  Audio_ALL.state==OFF){ postUpdate(Audio_ALL, ON)}
    if (Port1_2.state==OFF && Port2_4.state==OFF  &&  Audio_ALL.state==ON) { postUpdate(Audio_ALL, OFF)}