Best way of setting individual playback timings for multiple transports

Hello I’m newbie for juce framework and student trying to make simple daw for my project. Currently i implemented multiple wav file player with one record track with AudioAppComponent(from juce tutorial-simple audio player). read and play wav files with multiple transport sources that added to one mixer source.

void MainComponent::getNextAudioBlock(const juce::AudioSourceChannelInfo& bufferToFill)
{
    //bufferToFill.clearActiveBufferRegion();
    mixer.getNextAudioBlock(bufferToFill);
}

And the play and stop functions are implemented through the for statement.

for (int i = 0; i < maxTrack; i++) {
                transportSource[i].start();
                transportSource[i].setPosition(0);
            }

I have in trouble with setting individual playback timing of each transport source. for example, i want to play transportSource[0] at first, after 2.5 seconds, play transportsSouce[1].

Since I am implementing the file output function, I hope that each playback timing is reflected in the mixer source.

I have no idea to implement this function… so is there anyone who can teach me a good way?

Thank you. Sparkle

ps. can i make empty but playable transport source?
ps2. best way to crop function of transport…