Square one, slangily

• In America, start to win game
• Very start
• Outset, slangily
• Time to tuck into scrambled egg - and nothing more - first thing
• Beginning, so to speak
• Very beginning, so to speak
• Very beginning, informally
• Outset, so to speak

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