I used to text a student the night before a lesson reminding him that we would meet the next day and he always replied, ‘OK, I am ready.’
I thought it was funny. I imagined him sitting there in his coat waiting for the lesson. 12 hours before it started! You see – being ready means ‘Right, let’s go, there’s nothing stopping me from leaving now.’
Saying ‘I am prepared’ means something slightly different. It means that you have done something to get yourself ready – for example you have packed an umbrella in case in rains – you are prepared for rain. Or perhaps more commonly, you have studied or spent time working on something so that you can deliver a good performance. E.g. I spent all week revising my notes so now I am prepared for my exam.
Since my student never did his homework, he was never prepared for the lesson. So the best thing he could have replied was – OK, see you there! That’s not as funny though…