How can I limit a list based on a custom date field
Actually you should be able to specify your custom field as part of the chained element criteria:

{% set currentAndFutureEvents = craft.entries.section('events').eventDate('&gt;= ' ~ now).order('eventDate DESC') %}


Source: https://plus.google.com/111247306448293182882/posts/Uu6ZuTH1NBu