Each Comune around the region of Abruzzo Italy work at different paces. Standardly for small works approximately 3 months for approval, larger projects can take as long as 6 months to a year. In Penne they seem relatively fast. It depends who presents it, whether it would be a local architect geometra or a well known celebrity.  My advice is to contact a well known local architect or geometra, who has the full knowledge of the Comune requirements. Therefore making the whole process simpler.
Generally you will need a new planimetria (plan of the house drawn) as it is prior to commencing works, a list of works (computo metrico) should your property be in the countryside, in yellow or red zone you will need a geologist test. There are no short cuts to foreigners getting planning permission in Italy, recently we worked in Cugnoli (PE) and their Comune was very rigid, also Montebello di Bertona  e Loreto Aprutino. Should you require any help to have your project approved or you require a first class architect don’t hesitate to contact Craftsmen of Abruzzo.