Set initial value for bootstrap checkbox button

See Bootstrap's bleeding-edge docs:

Pre-checked options need .active

For pre-checked options, you must add the .active class to the <input>'s <label> yourself.

Looks like you are missing the 'active' class in the second label. Is this what you were looking for?

<div class="btn-group" data-toggle="buttons">
    <label class="btn btn-default">
        <input type="checkbox">Hello 1
    </label>
    <label class="btn btn-default active">
        <input type="checkbox" checked="checked">Hello 2
    </label>
    <label class="btn btn-default">
        <input type="checkbox">Hello 3
    </label>
</div>