This is a sample only. The images crossfade much too fast here.

Can the Sequence be:

- All three images appear together on load

- Minimum 5 seconds no animation

- Center square crossfades [~1sec] to new image with 15 sec before the next center square crossfade

- After 5 seconds right square crossfades with same subsequent timing as center square

- After 5 seconds left square crossfades with same subsequent

 

Ideally no two squares are crossfading at the same time. 

Let me know if this poses problems.

These timings are suggestions only, they don't have to be exactly 5 seconds. Whatever you think works best.