The indicator is turned on in advance, but it must not mislead others. Although a right turn at the intersection is 
You intend to stop right after passing through the intersection. Under the Rules (clause 36), your signal must not mislead other road users. If you turn on the right turn indicator before the intersection, other drivers (for example, the one waiting on the crossing road) may wrongly assume that you are about to turn right at the intersection itself, even though a right turn there is prohibited by the “No right turn” sign (
Option 1. Turning on the indicator before the intersection will mislead others into thinking that you are turning right at the intersection itself.