Thanks to @Gerben's post came to know there are two events show.bs.tab (before the tab is shown) and shown.bs.tab (after the tab is shown) as explained in the docs - Bootstrap Tab usage
An additional solution if we're only interested in a specific tab, and maybe add separate functions without having to add an if - else block in one function, is to use the a href selector (maybe along with additional selectors if required)
$("a[href='#tab_target_id']").on('shown.bs.tab', function(e) {
console.log('shown - after the tab has been shown');
});
// or even this one if we want the earlier event
$("a[href='#tab_target_id']").on('show.bs.tab', function(e) {
console.log('show - before the new tab has been shown');
});