If they were cast down long before the events in Genesis took place, then how did Satan appear before the LORD in the book of Job:
Job chapter 1
[6] Now there was a day when the sons of God came to present themselves before the LORD, and Satan came also among them.
[7] And the LORD said unto Satan, Whence comest thou? Then Satan answered the LORD, and said, From going to and fro in the earth, and from walking up and down in it.
Again:
Job chapter 2
[1] Again there was a day when the sons of God came to present themselves before the LORD, and Satan came also among them to present himself before the LORD.
[2] And the LORD said unto Satan, From whence comest thou? And Satan answered the LORD, and said, From going to and fro in the earth, and from walking up and down in it.
???
We know from internal evidence within the book of Job that Job lived some time on this side of Noah's flood (For example, we read of "the Sabeans" and they were the descendants of somebody who is mentioned in Genesis chapter 10 on this side of the flood) and Noah's flood happened more than 1,600 years after Adam was created/made/formed, so how did Satan have access to heaven at this juncture in time?
In regard to what Jesus said about Satan, we read:
Luke chapter 10
[1] After these things the Lord appointed other seventy also, and sent them two and two before his face into every city and place, whither he himself would come.
[2] Therefore said he unto them, The harvest truly is great, but the labourers are few: pray ye therefore the Lord of the harvest, that he would send forth labourers into his harvest.
[3] Go your ways: behold, I send you forth as lambs among wolves.
[4] Carry neither purse, nor scrip, nor shoes: and salute no man by the way.
[5] And into whatsoever house ye enter, first say, Peace be to this house.
[6] And if the son of peace be there, your peace shall rest upon it: if not, it shall turn to you again.
[7] And in the same house remain, eating and drinking such things as they give: for the labourer is worthy of his hire. Go not from house to house.
[8] And into whatsoever city ye enter, and they receive you, eat such things as are set before you:
[9] And heal the sick that are therein, and say unto them, The kingdom of God is come nigh unto you.
[10] But into whatsoever city ye enter, and they receive you not, go your ways out into the streets of the same, and say,
[11] Even the very dust of your city, which cleaveth on us, we do wipe off against you: notwithstanding be ye sure of this, that the kingdom of God is come nigh unto you.
[12] But I say unto you, that it shall be more tolerable in that day for Sodom, than for that city.
[13] Woe unto thee, Chorazin! woe unto thee, Bethsaida! for if the mighty works had been done in Tyre and Sidon, which have been done in you, they had a great while ago repented, sitting in sackcloth and ashes.
[14] But it shall be more tolerable for Tyre and Sidon at the judgment, than for you.
[15] And thou, Capernaum, which art exalted to heaven, shalt be thrust down to hell.
[16] He that heareth you heareth me; and he that despiseth you despiseth me; and he that despiseth me despiseth him that sent me.
[17] And the seventy returned again with joy, saying, Lord, even the devils are subject unto us through thy name.
[18] And he said unto them, I beheld Satan as lightning fall from heaven.
[19] Behold, I give unto you power to tread on serpents and scorpions, and over all the power of the enemy: and nothing shall by any means hurt you.
[20] Notwithstanding in this rejoice not, that the spirits are subject unto you; but rather rejoice, because your names are written in heaven.
Jesus' comment regarding Satan falling as lightning from heaven is understood by some to mean that as the 70 were casting out demons in Jesus' name, Jesus was beholding Satan's kingdom suffering damage. Others understand this to mean that Jesus was actually warning the 70 about PRIDE in that they were rejoicing that demons were subject unto them and Jesus was reminding them how PRIDE precedes a fall. In any case, I'll be happy to show you other scriptural examples where Satan and his angels have access to the heavenlies if need be.