You have to pull out meta-time, in that case, but first-cause is
still a valid point against ANY explanatory system. You can
always step back and say "But what created THAT?" There is no
satisfactory explanation. God is a cop-out in that respect, and
vulnerable to the same argument (except that theists define God
to be "that which answers the first-cause argument", and think
they have said something profound).
Thinking in terms of dimensions, your first-cause could be operating in larger dimensions. And a God opperating in more dimensions that has "always been," is as plausible as a universe that has "always been."