It seems that it gets scheduled, and doesn't start until your current program (the perl script) is done.

It should start immediately, and it does so in my experience. In the following program, you can see that the parent and the child are executing concurrently.

#!perl -l
system 1, q/perl -le "print 'child'; sleep 2; print 'child'"/;
sleep 1;
print 'parent';
sleep 2;
print 'parent';
[download]

outputs

child
parent
child
parent
[download]

Also: where is the 1, part of the system command used on windows described. A pointer??

perlport. Search for system(1, @args).