The phrase "glacial inception" refers to the starting point or beginning of a glacier. It describes the moment when ice begins to accumulate and transform into a glacier over a long period of time. Full definition
2007/04/23: ClimPast: Northern hemisphere winter storm tracks of the Eemian interglacial and the last glacial inception by F. Kaspar et al.. (illconsidered.blogspot.ru)
Ganopolski, A. et al. (2016) Critical insolation — CO2 relation for diagnosing past and future glacial inception, Nature, doi: 10.1038 / nature16494 & Crucifix, M. (2016) Earth's narrow escape from a big freeze, Nature. (carbonbrief.org)
The argument in the new paper is interesting, attempting to use the paleoclimatic record to quantify the threshold for glacial inception. (dotearth.blogs.nytimes.com)