WhatsApp will allow hiding the time of last visit from certain users
WhatsApp currently offers three options for displaying your last visit status, profile picture, and information about you. The messenger allows you to make them visible to all users with your phone number, hide them from all users or make them visible only to users in your contact list.
So, if you want to hide your last visit time from certain contacts, you have the option to hide it only from all or limit visibility only to your contacts and remove those extra "certain" contacts from your phone. But that may change soon.
WhatsApp is reportedly working on a new visibility option that will allow you to hide your last visit status, profile images and information about you from certain contacts. According to a source, the messenger is currently testing a new "My contacts excluded" option that will allow you to specify which contacts you want to hide your details from.
At the moment, the new option is not available in the current beta version of WhatsApp. But it should appear in the beta versions of WhatsApp for iOS and Android soon.
Source: wabetainfo