If you have a tower the lines are probably getting warm in the tower and the first glass will be foamy until the lines cool down or you may need a bit more line to equalize the pressure.
I have roughly the same setup you describe with a two tap tower and I get a half a glass of foam with the first glass. I just don't worry about it. Also you may be over carbed which will balance out over time under the 8-10 psi. I usually force at 30 psi at room temp and only 15-20 when the beer is cold.
5/16 or 3/16 beer line? If it's 5/16, you'll need longer lines... Line balancing or beer length calculator search should bring up some helpful info.
If it's just your first pull, RDWHAHB- work on keeping your lines cool is about all you can do, the CO2 will still come out of solution a little as it sits in your beer lines.
First Beer Foamy
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