const now = new Date();
    const start = moment(now) // get current datetime
        .utcOffset(0) // convert to UTC
        .subtract(24, "hours") // go 24 hours into the past
        .startOf("day") // get the start of the date we landed on
        .unix(); // get unix timestamp
    console.log(now);
    console.log(start);

Sat Apr 20 2019 15:11:23 GMT-0400 (EDT) {}
    1555650000