i always prune mine when young
they will send out several branches, but you can prune those as well
leaving 1 or maybe 2.
it will also try to produce twice as many fruit (more branches = more fruit)
with twice the growing tips, but i cull %30 or so of the flowers
the plant gets a bit wider, since you have leaves growing out from more than 1 spot
and sometimes at different levels (height), which can increase the ability to harvest the sun
but you also get leaves running into each other or not being able to grow out properly.
so there are pluses and minuses...
but i tip them pretty often to control height.
they can get "unruly" if you tip them too much
and dont prune off some of the other leaders...