Timestamps are in ISO8601 (https://en.wikipedia.org/wiki/ISO_8601). Constantinople is currently targeted for February 27, 2019, according to https://www.reddit.com/r/ethereum/comments/ahb93v. Fork is considered successful if both the latest Geth and Parity clients, as of 2019-02-28T00:00:00Z, support the Constantinople fork, and if the forking block in question happens prior to 2019-02-28T00:00:00Z. The amount of nodes following the Constantinople fork will have no bearing on this market.
Augur Market ID