Most people worry about the Clock, don't.
If you used to shooting on a timed lane it should be ok, but if this is the first time just ask your partners for calls at
1 min (elapsed)
1.min 30 secs,
and last 10. should give you all the warning you need on time.
If the target looks long, say 50y, once sat down, load the gun, set the dials for 50 before you start range finding, if it is 50y, your already loaded and dialled in once range finding has confirmed the range, so a quicker shot can be got off.
In the first few lanes you shoot, the plates & kills will be fairly clean. If your first in your group to shoot a target, presuming its gone down, ask your partner(s) to confirm the hit and then re-set the target to check the pellet impact point, did you have the right height, wind etc.
If you miss and hit the plate that will also give you an idea of went wrong that time. adjust for next shot.
Don't worry about what you score. Its you against the course, not you against other shooters be they the same grade as you or not.
Long shoots (3 hr) so water or similar to drink going round and perhaps a small snack. (before anyone says it that's not a McD for me, that's on the way home lol)
Above is the most important factor, make new friends
After the shoot work out what went wrong
I keep a little note book with me and make notes of what I missed, usually gives you a pattern of things to work on,
i.e. you miss all 6 standers on sunday, it don't matter, it just means you need to work on standers.