Many people use an ice cream scoop to measure cookie dough, but these sound a bit like fairy cakes?
Personally, I would start by doing a smaller batch, (say 2 or 4) so that I didn't waste too much if it didn't go so well.
I'd use a measuring jug to mix the mixture, having laid out the correct number of cup cake papers.
Pour some mixture into each paper, guessing about half of the finished quantity, then go back around the four papers again until they are filled to the same level.
Memorise the level in the paper cases.
Unless you are trying to change from several cupcakes to a larger cake or loaf shape, there should be no difference in the cooking time.