It's hard to answer without knowing what way to cold is. Different yeast have different temp ranges. And some yeast are very hard to tell if fermentation is going on without hydrometer readings, when the temp is in the low range. This is because the fermentation will be slower at a lower temp.
That said, if it doesn't start on it's own and once the must is up around 70°, I'd make a starter (One packet of yeast, a pinch of nutrient, 2 tablespoons sugar, in 1/2 cup of lukewarm water in quart jar). After yeast gets started then slowly add some of the must (about 1/2 cup) and keep doing this every 15 to 30 minutes until the quart jar is about full, then add it all to the must. Oh, don't seal the jar just cover with a clean cloth.