How long does it takes to get the PADRON document?

This depends on your Ajuntament, but is usually a couple of days in the small village where I am, so long as you provide them with the documents they want. (Renewals, when needed, are available the same or next day.)

Ask first what documents they need and see if you have them. (Normally passport, NIE certificate & proof of residency such as title deed or rental contract. The latter may need to be translated if it isn't in Catalan or Spanish. They may also want a water or electricity bill.)