Great, and hey we all get it mixed in our head at times, I know I do often enough! Since leaving longer got you starting easier, chances are one or more of the glow plugs aren't working. Test each one, you should get resistance to ground from the tip of each plug. I did a howto video a whole back on testing and replacing. They're cheap enough, but one of the 4 plugs are a pig to get at (left most, behind alternator). If you're lucky and have the right shape/angle sockets you can do it, otherwise it's Aux belt loose, alternator moved job. All DIY do-able though, just take your time so you don't snap them in their housing.