How many days before H4 EAD renewal can be filed: 180 days or 120 days before current card expiration?

My current H4 EAD card is going to expire on 17th March 2019. How many days before expiration of my current EAD card can I file the renewal application? On USCIS site it mentions as 180 days. Is this correct?

Also my spouse has got his Green card amended with the same employer because of the recent move to a new facility. Will the old I-140 approved notice hold good for the H4-EAD renewal?