This may be personal, or it may be an American preference that is shared by my countrymen, but I don't like "Kindly" in place of "Please."
Please refrain from talking during the performance.
Please do not use flash photography in the museum.
When you replace these with "Kindly" it sound patronizing to me. You could have said "No talking!" or "No flash photography!" with the same meaning and whether I am "kind" as I obey your command is irrelevant.
That said, I have never seen "kindly" used in this type of imperative anywhere but before the verb. Kindly refrain, kindly use, kindly help, kindly etc.
Kindly help us keep the area clean by properly disposing of your trash.
NOT Help us keep the area clean by properly disposing of your trash kindly.