Praise be to Allaah.
Allaah has created Paradise and its creation is complete, because He says in a hadeeth qudsi: "I have prepared for My righteous slaves that which no eye has seen…" And because the Messenger (peace and blessings of Allaah be upon him) saw it on the night of the Israa' and Mi'raaj, and because of other proofs (daleel).
Will any humans enter it before the Day of Resurrection?
There are two aspects to this:
1. Entering it in spirit only, as is the case with the dead. This is proven in the case of the Prophets, and of the martyrs (shuhadaa') whose souls are in the crops of green birds which roam about in Paradise. This is also known from the ahaadeeth in which the Prophet (peace and blessings of Allaah be upon him) describes how he entered Paradise in dreams, which has to do with the soul or spirit.
2. With regard to entering Paradise in both body and soul, this will happen on the Day of Resurrection for both humans and jinn. The only exception to this is Adam (peace be upon him) who was in Paradise before he came down to this earth, as was mentioned by Ibn al-Qayyim and others. And Allaah knows best.
Sheikh Muhammed Salih Al-Munajjid