Squeeking sound at cold / morning start is quite common problem in Vios 1st generation (model code NCP42) and 2nd generation (model code: NCP 93).
The cause is the fan belt / V belt . The original supplied by Toyota is Mitshuboshi brand (not to be mistaken as Mitsubishi). You may try other brand such as the long and trusted Bando or Dyco for a change. Years ago in Waja, the ori factory alternator supplied is Mitshuboshi and it was the 1st that make squeeky sound compared to the other belts using Bando. Yes, Proton uses different brands for V belt from factory.
There is nothing special about using Original Toyota packing V belt (colloquial known as fan belt) as there are only a handful supplier for belt. For Japanese car, they either use Bando or Mitshuboshi as both are Japanese companies. I would prefer to use Bando rather than Mitshuboshi .