Matter can be observed, either by the eye, by instrumentation, or by test. We can neither observe nor test God. And besides, if God created matter, then God supersedes matter. So, God is not physical. Nor is God bound by time.
Time is a human invention to measure finite events.
Time, in concept, has no beginning, nor an end. When God created humanity, God created time by default. And if God created time, then God supersedes it as well and is not controlled by its conscripts. We can know God only by what God reveals. God spoke to Moses and Moses asked who God was.