Handle case where no proms have been created when joining job.
Default to a much smaller AOT - this should be modifiable for platforms.
Comment out reload button (this should only be available for dev purposes)
Allow synth trigger sched_ahead_time value to be modified:

* Default for Raspberry Pi is 0.5s
* Default for all other systems is 0.1s
* Modify value with `set_sched_ahead_time!`
Add quick (potentially hacky) job joining method. 

TODO - check for concurrency issues with this approach with more rigour
       when not on a train preparing for a talk...