Hi Antonio,
if you want to use the custom attribute in the start expression you must declare it being a startd_attribute - I think, try:
STARTD_ATTRS = $(STARTD_ATTRS), CustomStatus
Also you might want it to set static in the config as there might pe a short period at the start of the machine were condor_cron has not run yet but condor is already running, put
CustomStatus = "foo"
Or as an alternative solution to that problem configure a one-shot-cron-run right after condor start, I don't have the syntax for that in my head but you will find the solution in the manual ;)
Last thing I think I am spotting is you need to put:
STARTD_CRON_myjob_MODE = Periodic
Also the startd logfile should give you some insight about the run status of your cron job ...
Best
christoph