Every chance you get! LOL. The philosophy here is "the more the merrier". When your trying to conceive you might as well have as many soldiers in the race as possible. Also, just as a tip, if you want to up your chances of conception you should also start having sex a couple days before your fertile window. Sperm can live for several days and if there are already men waiting outside the ovary to ambush the egg when it shows up then yay! Now there is a theory that if you want to have a girl, have sex before you ovulate and if you want a boy have sex when you ovulate. That's because research suggests that male sperm (ones carrying the 'y' chromosome) are very fast and will reach the egg first but also die off quickly. So if you want a girl, have sex long enough before hand that the male sperm will be dead and if you want a boy, have sex as soon as you know you have ovulated an they will get there first. Good luck!