Tone sequencer without using delay

Using Arduino Audio
#1

Hello,

I am trying to make an audio sequencer but without using delay. I have been trying with millis() but I cannot seem to get it to work . What I intend is simple:

Play tone 1 with a specific duration
delay(tempo)
Play tone 2 with specific duration
delay(tempo)
Play tone 3 with specific duration
delay(tempo)
Play tone 4 with specific duration
delay(tempo)

I can achieve this only with delay() but when I try to incorporate millis() things don't work as intended.

Here is a portion of the code I am trying unsuccessfully inside void loop:

unsigned long timenow = millis();

if ((timenow - timestart0 >= seqtempo)&&(playtone == false)){
tone (speakerPin1, NOTE_A4); // Start playing tone
playtone = true;
timestart0 = timenow;
}

if ((timenow - timestart0 >= toneduration)&&(playtone == true)){
noTone (speakerPin1); // Stop playing tone
playtone = false;
}

if ((timenow - timestart0 >= seqtempo)&&(playtone == false)){
tone (speakerPin1, NOTE_B4); // Start playing tone
playtone = true;
timestart1 = timenow;
}

if ((timenow - timestart1 >= toneduration)&&(playtone == true)){
noTone (speakerPin1); // Stop playing tone
playtone = false;
}

if ((timenow - timestart1 >= seqtempo)&&(playtone == false)){
tone (speakerPin1, NOTE_C4); // Start playing tone
playtone = true;
timestart2 = timenow;
}

if ((timenow - timestart2 >= toneduration)&&(playtone == true)){
noTone (speakerPin1); // Stop playing tone
playtone = false;
timestart0 = timenow;
}

}
}

#2

Other post/duplicate DELETED
Please do NOT cross post / duplicate as it wastes peoples time and efforts to have more than one post for a single topic.

Continued cross posting could result in a time out from the forum.

Could you take a few moments to Learn How To Use The Forum.
It will help you get the best out of the forum in the future.
Other general help and troubleshooting advice can be found here.

#3