from datetime import datetime, time, timedelta

def get_custom_today(now=None):
    now = now or datetime.now()
    cutoff = time(18, 0)  # 6:00 PM
    if now.time() >= cutoff:
        custom_day = (now + timedelta(days=1)).date()
    else:
        custom_day = now.date()
    return custom_day