It all depends on the pair,.. I have had clowns lay eggs within a year and some,.. never laid eggs. However there are things you can look for to tell if they are a potential pair or not. For example,.. if you put in two clowns and they never had a single fight,.. chances are they will not become a potential pair... its the repetitive aggressive gestures without submission that help stimulate the hormones which trigger sexual development. A pair that constantly reenforces its order is most likely to be a successful pair especially when bickering smooths out to a simple glance from the female and very quick tilt and/or quiver from the male. You can tell when they are ready to breed from their behaviors,.. The female tends to get less aggressive with the male and starts to feed more often. The male starts to become more over all aggressive and defends a the area from unwanted company. They also will stay very close to each other. Together (although most cases I see the male do it more) they will clean off (usually vertical) surface for eggs to be deposited on. You can also catch them doing practice runs,.. They will go through the same motions they do when they lay eggs but they just make the motions,.. its kind of neat. They can be in this stage for a while though,.. I actually have two pairs that have been doing that for months. However there are ways to stimulate the process. The usually like to lay the eggs in the spring because this is when their food source is usually at its peak. You can actually simulate spring over a period of a month or two by doing a few things. Very slowly and safely increasing the temp, increasing the day light hours, increasing food source (this is the time you want to make sure they are getting everything they need,.. read Joyce Wilkinson's book for great information about their diet!) and lastly,.. decrease the salinity. Why decrease the salinity? The oceans salinity slowly decrease in the spring because of snow melting. Over all the most important thing is consistency. They love to be fed at the same times everyday too. Only bad things happen fast, enjoy the ride and be aware not all pairs are compatible. Do your best to provide great water quality, good food, consistency, a host and friendly tank makes. Best of luck.