Underspeed Limiting

I have a technical question regarding approaches. I've read through the sections of FCOMv2 (Section 4) that talk about underspeed limiting but I'm not sure if the MCP indication indication for this situation is normally encountered in approaches. I notice the underspeed MCP indication (flashing" "A) when I am in an ILS approach and I set the IAS selector to VREF+5. I then reduce speed and add flaps to get down to this speed. Should I hold off setting this speed until I get to a configuration that will allow this speed without violating any minimums or should I go ahead and set VREF+5 and have the indication until I get down to a non-underspeed condition? Thanks.