1) Go to Extentions --> Plugins --> and click ' ajax - DT Set Available Time'
2) Inside the plugin, these is a field call 'Hikashop Category'. You may select a specific Hikashop Category to set your available time. By doing so, other hikashop category's product won't be affect.
3) Go to Component --> Hikashop --> Products
4) Select a product that you would like to set the available time
5) Scroll to the bottom you will see 'Weekday', 'Time From' and 'Time To'. Weekday you can choose from 'Monday' to 'Sunday'. 'Time From' and 'Time To' can choose '11:00' to '21:30'.
6) Every 12 a.m., system will auto update the 'available from' based on the wekkday, time from and time to you choose