setting clocks

Your solution is very bad and would probably result in the tournament director having to get involved.

Most modern digital clocks can handle complex time controls. Try reading the manual. 

Unfortunately, Steve, I don't own a DGT -- at least not yet -- but I own an Excalibur Game Time and also a Mephisto Competition Pro. I just checked and both have these preset time controls: an initial preset of 40/90 and a second preset of SD 30. If your clock doesn't have these exact presets, but I imagine it does, you can use the closest presets and then adjust manually.

Regarding the 30 second increment, you can choose between an add before move or pre-move increment and an add after move or post-move increment. Oddly, some tournament directors don't know the difference or care like one I asked in Colorado.

To be specific, in the first case the increment is added to your side after your opponent presses his clock and in the second case the increment is added to your side after you press your clock. Frankly, it doesn't make much difference until you have 10 seconds left. The pre-add method would give you an additional 30 seconds up front for a total of 40 seconds to make your next move whereas the post-add method leaves you with only your original 10 seconds before defaulting on time. Of course, if you can get your move in before the flag falls you'll get an additional 30 seconds and you're back in business. By the way, the increment can be set for the first time control alone or for both.

You may want to ask the tournament director ahead of time if 1) the increment is for both time controls, and 2) if the increment is pre-move or post-move? Your DGT, which I know is more flexible than my Excalibur and probably similar to my Mephisto, should accommodate this and more.

Unfortunately, I can't speak for the manual on your DGT, but the Excalibur and Mephisto are not outstanding but sufficient.

I hope this helps.

Best,
Bob

P.S.  Here is more on the increment from move 1 at Wikipedia.

I also have a DGT clock, and as an old timer I’v had to scratch my head a few times while setting it. The guide on the back of the clock helps a lot. If I have any doubts about whether it’s set correctly, I do the natural thing: I ask a teenager to check it. They usually smirk a bit but they do it gladly.