Spain has not really banned Telegram. It has instituted a temporary restriction while the company appeals. However, this restriction isn't really enforceable, because it must be implemented within 3 hours of the ISPs receiving the ban notice. However, ISPs can only receive these notices oficially on working days, and right now they're celebrating easter.
Telegram has 3 days to appeal the ban, and it probably will appeal before ISPs start blocking it. The appeal will most probably be accepted (as Telegram is an important company, and many people there use it as their only messaging app).
Thus, the ban will probably be lifted even before ISPs start blocking Telegram, unless something goes terribly wrong.