For anyone wondering why she needs to use the hourglass for that is because she needs to hide her intentions. After all she’s speaking to one of her sister’s close maids about a maid that is not her own. It’s rather suspicious of her to be questioning about another maid so thoroughly and it would be best if the maid she was speaking to did not report it to her sister as to keep them clueless on any inkling of a plan she might have