As a mum of twins myself I've done a lot of research regarding twin pregnancies. If you are not using any fertility treatments there is little chance you can actively 'try' to fall pregnant with twins. Most people who do fall pg with twins 'naturally' do so because they have inherited the gene to multi ovulate (fraternal twins) and identical twins are more a chance occurance i.e. no way to choose to have identical twins, and not inherited either.

If in fact you are talking about Implanon, then as the previous posted replied you are not covered by any contraception from the day it is removed, however, as with all contraception some ladies are able to fall pg right away while others take a while for their body to get back to 'normal'. Either way, I hope you get what you want