I agree with Andy Taylor's comment regarding not closing pneumatics when
hinging, and would even add that it is best to wait until the glue is
completely cured (24 hours), before collapsing the pneumatics.

If this is done and the work is good, almost no outline of the boards
will be visible on the cloth surface -- the pneumatic will "box out,"
free of stresses.

In some ways, hinging is the most critical part of covering pneumatics.
If no "axial" squeeze-out were left from covering the sides, it might be
best to do hinging the following day, for optimal results.  In this case,
and if no glue were permitted to squeeze as far as the internal board
edge at the hinge, it would be safe to hinge with the pneumatic closed,
without causing it to pull closed.

However, as at the sides or front, stresses could still occur if the
cloth were stretched excessively, or wrestled around and not laid onto
the wood in compliance with the grain of the fabric.

Larry Broadmoore