There are no lock-in periods for smallcases, so you may sell your investments at any time. However, smallcases work best when used for long-term investing. There are no recommendations provided on when to buy or sell a particular smallcase. It's upto each investor to decide which theme will work and when to buy or sell 

For smallcases, the stock selection for a theme is a result of well documented research processes and it's ensured that the selected stocks aptly represent the particular theme. Sometimes markets over/under-react to events in the short term which should auto-correct with time. You might make more profit by selling before an event or after. You would be notified when the theme of a smallcase you hold has completely played out or factors driving a particular idea/model have changed