I wouldn't mention hour building. At LAX, I have just said I'm here for a holiday, and will do some travelling.
If you really are intent on spouting forth about your flying plans, have the mobile & home phone number of the school owner, or the CFI, and their main office number with you. (In case you land out of hours). There was a case of someone turning up and spending the night in the cells at LAX because the immigration people couln't contact the CFI/owners to verify his story. As soon as they contacted the owner, he was allowed to continue.
My policy has always been to be tight lipped, and look like a tourist.