All times are in GMT, Greenwich Mean Time. You can check the current GMT by googling "GMT". If your PTS ownership, or your AGS donations are reflected in the PTS blockchain or the BTC blockchain as of the last block mined on or before 23:59:59 GMT on February 28th, it will be counted. If it is in the next block, it will not be counted.
At the time of this post, there are slightly under 20 hours remaining before the snapshot.