Their attitudes do suggest they are preparing to lay but...... some fish don't have successful batches till after a few months. ESPECIALY if they don't have the right diet. They will protect that one area months before their first lay BTW. The biggest thing to look for would be The male fanning a particular rock with his fins (facing the rock) not his tail. He will also "blow" on them (i quoted blow due to the lack of a beter word). This is the #1 sign if you cannot see the eggs you know the eggs are there if the male is doing this. Other signs like picking at a rock, agression around a certian area, are all signes of breeding, but they will do these things before they lay as well. So your best bet is to look for the eggs cause if u cant see them chances are they will hatch without u knowing and be swept away by your filter system. You also need to be able to see the eggs to judge their heithieness, and time of birth so you can shut your system off and catch them the day of the hatch.
Conclusion: Either way if you want to rear clowns you have to be able to see the eggs.
Suggestion: put a piece of porcelin (or 2) inside the tank where they seem to be protecting. if you feel like you want to have an ugly flowerpot inside your display tank then these work best for breeding due to structure so they can hide =). but squares of porcelin will work too. 90% of the time they will choose this surface to clean and attatch their eggs to.
If you have any questions feel free to ask. If your fish havn't layed yet it seems they are close and they want to.