Is TEMP COMP available in your FMS? If so, follow those altitudes once the temp deviation is loaded and activated. If not, compute the temp correction, advise ATC of the indicated altitude being flown for the existing temp. Canadians an d most cold weather areas, except the US, understand the need for temp comp.
You comp for all altitudes from IAF inbound. Set the ALT SEL to the corrected altitude, VNAV, if the VNAV can be temp comped, will follow temp corrected altitudes.