Exodus 7:4 But Pharaoh shall not hearken unto you, that I may lay my hand upon Egypt, and bring forth mine armies, and my people the children of Israel, out of the land of Egypt by great judgments.
God knows the future, today, and yesterday. They are all the same to Him. He has promised to bring Israel out of Egypt and He will do just that. He will bring things and events to pass to accomplish His purposes.
Moses can be sure that the job He is being sent to do will happen. God is at work.
You can know as you step forth to the ministry of serving God that He will accomplish great things. Rest assured that you serve a great God well able to accomplish His purposes.
Go in faith knowing that God is at work!