Short answer: one.
To many Christians this might seem an odd question. Everyone's heard of the Second Coming--and everyone understands that to mean Christ is physically coming back once more. No one ever talks about a Third Coming, do they? But it's important to establish that He's only coming back one more time because there's a popular doctrine today that teaches otherwise.
Let's look at some sample verses that clearly speak of Christ's physical return:
"...those who are Christ's at His coming" (I Corinthians 15: 23).
"...blameless until our Lord Jesus Christ's appearing" (I Timothy 6: 14).
"...be patient brethren, until the coming of the Lord" (James 5: 7).
"...who will judge the living and the dead at His appearing" (2 Timothy 4: 1).
"...I will come again and receive you to myself" (John 14: 3).
"...that He may establish your hearts blameless in holiness before God our Father at the coming of our Lord Jesus Christ" (I Thessalonians 3: 13).
Notice all these verses speak of His "coming" or His "appearing"--never His "comings" or His "appearings." It is always a singular event. His return is never referred to in the plural. Christ Himself never suggests multiple physical returns, nor do any of the New Testament writers. They never hint at a Second Coming followed by a Third Coming. In fact, there is not a single verse in Scripture that refers to two or more personal returns. If two returns were planned we would expect to find at least one mention of this concept in Scripture. Yet there are none. We would expect to find at least one passage that plainly mentions both returns in the same discourse. Yet there are none. We only hear of one physical return: His second coming, when He leaves His Father's right hand in heaven to return visibly to earth.