Please note, all acrylic (sometimes referred to as Perspex) poles tend to deflect over time, especially with fluctuations in the weather / temperatures. For this reason we recommend you have a small drape of the curtain on the floor, always have a centre bracket and in cases of wider poles have passing brackets and passing rings to give added support at the quarter way point. From time to time you may need to turn the pole in the bracket and re-secure depending on the deflection. Over time the pole will straighten before needing to be turned again.
Add a minimum of 15cm either side, preferably more, but for full curtains or wide windows allow at least 25cm if you have the room, excluding finials (decorative pole ends).