No. ag fail isn't generally used that way. You would generally say tá bróga nua á bhfáil agam, if you are getting them right now. If you will be getting them later today, that's what you'd actually say in Irish (unlike English, where you can use the present tense for an action that will happen in the near future) - beidh bróga nua á bhfáil agam inniu - "I will be getting new shoes today".
(ag fail is used in some circumstances, but it seems to have negative connotations - ag fáil bháis seems to crop up a lot!)