This is because of the warmup command, which gives players some time before the match to get adjusted.
If you would like to turn it off, you can try this:
In the console (press the ~ key), type
/callvote g_doWarmup 0However, the server admins may set a warmup period on purpose - 1v1 servers often have a warmup period. If the command is votable though, knock yourself out.
This post should be under "Technical Snafus".