In a Test match, the pitch is rolled at the start of each day's play. When the ground provides multiple rollers, the captain of the side currently batting has the choice of rollers.
Captains use this as a tactic on the 5th day in suitable situations. For example, when the batting side has a substantial lead (and a good bowling attack), he may choose to not declare before Stumps on Day 4, so that he can use the heavy roller on 5th day morning which would give additional assistance to the bowlers later on.
My question is, is it allowed to declare the innings immediately after the pitch has been rolled, or does the batting side need to face at least one ball before declaring?