The port is open 270 e-shaft degrees from the first apex seal passing over it
to the next apex seal passing over it. 270/360 times 10.0 is 7.5 msec
However the next intake stroke starts to occur immediately.

You can also start to inject fuel just before the port closes and catch the
next rotor face intake cycle. A carb is feeding fuel 100% of the time
and the engine runs fine.

This is not like a piston engine. A piston engine intake stroke comes
to a dead stop for 270 crankshaft degrees. Not so in a rotary. The intake process
is in continuous state of operation. One or another rotor face is always
in intake position.

Part of that time it is open to the exhaust but the pressure in the tuned
intake manifold is higher than the pressure in the exhaust so no transfer
of exhaust gases happens during that time. At other times some exhaust gas
can get into the intake and vice versa. In effect the exhaust gas pressure
combined with the intake chamber pressure build up is used to bounce the
intake wave. What you need to know is what is the pressure where every
millisecond or so during the entire process.

When you see this happening on a dyno it is a very powerful effect.
Very impressive.

What Doug is up to is reducing the time the injector is open by using
a high flow, high horse power injector and upping  the fuel pressure from the
current 40 to 50 psi to something higher. That will give the same
amount of fuel for a shorter injector opening time.