when to test ?

When is a good time to test ? I've been let down for about 6 months now and I'm starting to worry again thinking il get another bfn.. I'm newly 45 and I've had 2 miscarriages within the last 2 years . Me and my Fiancé have had sexy daily since my last period February 15th ( sometimes a few times a day ) we are very sexual people who are madly in love of course :) honestly I don't see how we would fail this time but I don't want to get my hopes up to much . Any advice ?