Was Christ Preconceived?

I have given thought to the often-used term “ preincarnate” (before entering flesh) which seems technically inaccurate.

It’s a reference to appearances of Christ in the Old Testament. However, when Christ/Messiah appeared to Abraham and Joshua (Genesis 18; Joshua 5:13-15), it seems that He appeared in flesh long before being conceived in Mary’s womb. If so, the word “preconceived,” rather than “preincarnate,” seems a more accurate term. Since “with God nothing shall be impossible” (Luke 1:37), being in the flesh prior to Jesus’ conception is a possibility.

Question: Is it possible for God to use a temporary fleshly body to visit the earth

for a special purpose and decompose it when His work is done?

Blessings!