First moment

• Time to tuck into scrambled egg - and nothing more - first thing
• Very beginning, informally
• Beginning, informally
• Very beginning, slangily
• Square one, informally
• Beginning, in slang
• From the __: at the start
• Square one, slangily
• Day one, informally

Wiktionary Word definitions in Wiktionary
n. (alternative spelling of get-go English)