This is a genuine question, because I'm baffled how other people find the time - but I really want to!
DD is 4 months old now, and since she was born we've only had sex twice (and the first time was, predictably, rubbish). I had hyperemesis so we had practically no sex at all during my pregnancy. I had an emcs so I've no problems 'down below' that need working through, other than the fact that there's been nothing happening there for about a year... 
But when on earth are we supposed to do it?! When DP is at work he gets home just after 7 and does bathtime and bedtime for DD, and then we have dinner, so its about 8.30 by the time we've finished eating - at which point we are both far to full to contemplate sex! And then I go to bed at about 10 as I do the night feeds. DP's out of the house by 7am, so no time for it in the morning either while DD is asleep. At the weekend when we're both at home the problem is that DD is not a cot-napper (I'm working on this...) so she sleeps either on us or out walking in her pram - so to time there either... DG's are very helpful but none live near enough to just babysit for a few hours, so we need to plan for DD to go to them for a night - this is on the cards as we really feel we need a night out and some couple time, but this isn't a proper fix.
Sex used to be a big part of our relationship and while DP was very understanding during my pg that I wasn't remotely interested, its been a year now and I'd really like to get things back on track.
So, please, without sounding too dodgy, can anyone explain to me how they find the time to be alone with a 4 month old in the house?!