180 day is determined by the time they leave

the country. The stamp on the passort shows the date. Keep airticket,boarding pass to prove the date. Call CIS trying your luck to see if H4 is approved. But most likely, you will get nothing than the case is pending. If passing 180-day time line, they are not able to adjust status in the US, unless a new law passes or you become citizen . There will be a 3-year (or 10-year) bar on them. The consequence is very serious.