oliverdavies.uk/source/_includes/availability.html.twig

<div class="panel panel-default">
    <div class="panel-heading">Availability</div>

    <div class="panel-body">
        {% set now = "now"|date('U') %}

        {% for type, data in site.availability.status %}
            {% set text = site.availability.text[type][data.available] %}

            {% if data.start %}
                {% if data.start|date('U') > now %}
                    {% set text = text ~ ' starting ' ~ data.start|date('F Y') %}

                    {% if data.end %}
                        {% set text = text ~ ',' %}
                    {% endif %}
                {% endif %}
            {% endif %}

            {% if data.end %}
                {% set text = text ~ ' until ' ~ data.end|date('F Y') %}
            {% endif %}

            <p>{{ text|raw }}.</p>
        {% endfor %}
    </div>
</div>