Well done on completing Day 1, I doubt one will have that much of an impact, just make sure no milk moving forward though...oh and tablet sweeteners if you normally have sugar.
Be careful with the flavoured teas to - avoid fruit flavoured ones because of citric acid, green tea/peppermint teas are safe bets
There is a thread on what you can drink but you can have Coke Zero, Dr Pepper Zero, certain flavoured waters (look for ones that have malic acid and no citric acid) etc.