running event timing

You have to give each participant the same time of day start time. Just replicate the time in excel before you import. Then each participant in each group effectively starts in the same wave.

I believe you can also block edit the start times in the SST competitor screen as well.

The start times come in when you call for them in the running/mtb timing screen.

Experiment beforehand.

http://live-timing.com/race2.php?r=57841
The link above is a race from July 4 this year with about the same number of participants for a 5k-ish hill climb. One thing to be sure of is the use of the assigned and actual start. You can either import or it is very easy to assign start times in the software. Just make sure that you use the option button to copy the assigned start times to Actual start times for all competitors. Assigned starts will allow for the loading of the start queue but you will not get net times for participants unless they have an actual start time.

Fred and John are right.
Following are some notes I sent to Brian a couple days ago that might be useful to others in the future:

To set the start time [other than the method John mentions above]: Take note of the start time that everyone starts (the time on your timer) and set everyone by selecting a block of competitors on the competitors tab (all competitors if there's 1 start), take the block edit option and set the start time of day.
Don't use the "assigned start" for anything, that's used for specific types of cross country ski races.

I would strongly recommend using a push button for the finish rather than a photocell. Instruct the person with the push button to push it once for each person even if they're coming through in a group of three etc. And, set the delay to 1/10 or something small so each push button press will be counted.

Using the XC/MTB/ Running timing screen you can enter bibs before they arrive at the finish (when you know for sure there will be no passes) or after they cross the finish. Bibs or times will stack up and be matched up as you enter bibs or finishes happen. Have a play around with the timing screen to see how it works. You'll only need to deal with the finish column since starts would have already been assigned via the block edit.

Make sure you have a very controlled finish line. So, racers can't cross the line then wander away. Once they cross the line they should be funneled through so their bib can be recorded either on paper (and probably directly into the software) before they can go anywhere else.
I would suggest telling everyone at the start of the race:
- Make sure your bib number is visible when you cross the finish
- When you cross the finish stay in order
- Only cross the finish once, don't come through again with a friend or loved one!

Make sure you play around with the timing screen and the options. If you have any questions give me a call and I can explain how things work.