The difference between already and all ready
TLDR: Already means ‘by the time in question’, but all ready means ‘everyone is ready’.
No, these are not interchangeable. Fancy that. They do, in fact, have two different meanings!
already (adverb)—by now, by the time in question; a time earlier than expected; also used often in American speech as an expression of impatience
By the end of the first school day, Charlie had already lost his pencil case.
When Sarah arrived at the station, she couldn’t believe it was already three o’clock.
‘Get your coat on already! We’re going to be late!’
All ready, in contrast, is a phrase used to express the complete preparation of one or more people. For example:
Joan was all ready for school.
The children were all ready for their trip to the beach.
As you may have noticed, in these examples, the all can be omitted without damaging the meaning of the sentences. For example:
Joan was ready for school.
The children were ready for their trip to the beach.
As shown, the all is used as a word to emphasise just how ready Joan or the children are.
A good tip to remember, if you are having trouble with already and all ready, remove the all and see whether the sentence still makes sense. If it does, like the two examples above, then all ready is the phrase to use. However, if you end up with something which sounds strange, like ‘Charlie had ready lost his pencil case’, then already is the word to use!