The answers below were correct regarding VA as it is 2yrs. FHA is 3 yrs unless you were not late and you meet the other criteria for the new loan. Conventional has a tiered matrix:
2yrs = 80% LTV/CLTV
4yrs = 90% LTV/CLTV
7yrs = per the eligibility matrix
There is an exception regarding the 90% to be lowered to 2yrs however it is a case by case scenario. I've been lending for 27yrs and if you wish to tap my knowledge more, please contact me at your leisure.