Marital status as of Dec23 was married, but wife did not enter the US with her visa until March 24. Do I proceed as single marital status for purposes of taxes?

[Bsch4477]

No. Since you were married you have to file married jointly or married separately. I assume that you don’t have a dependent living with you. 

[sadlerdg]

No dependents and not a permanent resident (j1 visa)

[AmyC]

Since your spouse was a nonresident alien, you have the option of filing joint or married filing separately. To file joint, you need to make an election, see  Nonresident Alien Spouse | Internal Revenue Service. This is a common election.