I had an interview for immigrant visa under the category of unmarried sons and daughters of a us citizen. The consular officer approved my visa. I still am unmarried but wish to marry after I got my green card. My question is how soon can I marry after receiving a green card by going back to my home country?

You can marry at any time. I believe you mean to ask about your spouse, after you marry, also getting an immigrant visa, correct?

You can marry any time after becoming a permanent resident (you become a permanent resident the moment you enter the U.S. on your immigrant visa), and it won't have any effect on you.

However, you should not marry before you become a permanent resident because it will cause your category to change from F1 to F3 which has a few years' longer wait and any visa you have already been issued for F1 category will become invalid.

Note that if you marry after becoming a permanent resident, your future spouse won't be able to immigrate as your derivative beneficiary, and you will have to petition them separately as the spouse of a permanent resident, in F2A category, which has a wait of 1-2 years.