Help With Cantaloupe?

I have several cantaloupe growing (it's my first time) I have several on the plants.. there is one in particular that looks like a real full grown cantaloupe. Problem is it is small enough to fit in my cupped hand (I am a 5' tall female, small hands) do they usually look like this at this stage? do I have midget cantaloupes? How will I know when they are ready? they have that whitish bumpy stuff all over the outside. If you can direct me to a website with growth stage pictures I would appreciate it, I have went to several but all of the pics. seem to be of only one stage or just of vine growth. Thanks!!