Is it ok that i skipped a period on strattera (atomoxetine)?

Not harmful, but...: Atomoxetine is not a stimulant & does not work instantly. It can take several weeks at the correct dose before one notices benefit, and that benefit will diminish and eventually disappear if you are off long enough. Generally, barring unacceptable side effects, this medication is prescribed daily, even over the summer and definitely over school holidays. But, it's not dangerous to miss a dose.