EB2 vs EB3 after filing I-485 !!

[TheRealCanadian]

So when June 30 a visa is available. A person files I-485 on that day on EB3. Is that visa allocated to him on that day and will remain allocated as long the 485 is approved?

No. A visa must be available at the time of filing, but is not allocated until approval. Therefore, a visa must be available at approval as well.

My question as I filed before June 30(I dont have the receipt yet) are they working on some steps like FP on my file in July-Sep.

Maybe.