not every one lose it. n it means labor is near it you lost
I lost mine today 30+6 the doctor I seen at the hospital said it doesn't mean labor is coming and she said also it can grow back not to worry unless my contractions become regular or I start leaking or bleeding they said its nothing to worry about unless accompanied by other symptoms but you can lose it at any time while pregnant apparently
Theres really no specific time u can lose it at moment but more so toward the end..n it means u could be close to labor....idk if everyones plug is the same color but mine was like a brownish color