At 15-16 weeks with my twins, just a short couple weeks ago I started to feel movement mostly when I was lying down in a quiet area alone. Don't expect to feel 'kicking', it starts out as a flutter kind of feeling and new moms like us tend to write it off as gas or something. It is not that the movement is stronger in twins so you ought to feel it sooner but there is just more movement happening to be felt. It will happen soon enough.
I was around 19 or 20 weeks when I first knew it was babies movement. :)
HI,
For first time moms the fetal movements are felt at around 4th or 5th months or around 16 to 20 weeks of pregnancy. This varies from person to person. In case of twins fetal movements may be felt early because of presence of two foetuses.
Hope this helps.