Christians, how many heavens are there?

So it would appear.

-𝒞ℴ𝓇𝓋𝓊𝓈 ℬ𝓁𝒶𝒸𝓀𝓉𝒽ℴ𝓇𝓃ℯ

Just one. It is so far beyond the limits of human experience, or even human imagination, that those who attempt to describe it never come anywhere close to the reality. We live in an imperfect world, and cannot accurately imagine a perfect existence.

There isn't one for you, so stop worrying about it.

Exactly three.  They are distinct rewards for those who arise in the Celestial resurrection.  We don't have to imagine them, silly.

There is one Heaven. Heaven is wherever God is. There are however 3 earth and heaven ages. The first earth and heaven age was billions of years old.

Satan rebelled against God and 1/3 of God's children followed him. God ended the first world and heaven age because of this.

We are now in the 2nd earth and heaven age, a time of testing. God wants to see who will follow Him and who will reject Him. The 3rd earth and heaven age starts when God rejuvenates the earth and the eternity begins.

There are three and the third heaven is where God dwells.  Paul was caught up to the third heaven (2 Corinthians 12:2)  -  just once and he saw things he couldn't explain or mention and was not permitted to tell us or describe. 

 That's how holy it is in the third heaven where God, who alone has immortality, is invisible, dwells in UNAPPROACHABLE LIGHT, whom NO MAN HAS SEEN NOR CAN SEE" (1 Timothy 6:16)

Scripture references three "heavens"

Earths atmosphere

Outer space

Gods home "the third heaven" 

Well, currently the sky above you is “the heavens” and so is outer space above that....beyond that is the realm where God the Father and Jesus live currently, along with the good angels and good deceased people (the Holy Spirit is on Earth right now). In that order it’s the first, second and third heavens. The current abode of God is not His last abode, however. Jesus will reign for 1000 years on Earth after the defeat of Antichrist and the last war (Armeggedon), restoring the environment, ending the food chain and bringing world peace, before the final judgement. It will be a type of Heaven on Earth. Then God will create a combination

new Heaven and new Earth that will last forever, with no history of evil on it, and do away with the old Earth and Heaven.

3.  The near atmosphere.  The "heaven" past the atmosphere.  "Third heaven",  2 Cor. 12:2.

No, there's only one heaven.  See Revelation 21, especially verses 3-4 and 22-27.