God has always been God and has known everything that has ever been known so therefore He has always known all prayers that were ever said. This is implied throughout the entire bible. I have offered a few verses regarding my positon on salvation.
2 Peter 3:9
The Lord is not slack concerning His promise, as some men count slackness, but is longsuffering toward us, not willing that any should perish, but that all should come to repentance.
John 3:16
For God so loved the world that He gave His only begotten Son, that whoever believes in Him shall not perish but have everlasting life.
Matthew 7:7-8
Ask, and it shall be given you; seek, and ye shall find; knock, and it shall be opened unto you. For everyone that asks, receives. He that seeks, finds. To him that knocks it shall be opened.
Phillippians 2:13
For it is God who works in you, both to will and to work for His good pleasure.