Need help understanding sentence structure/Improving the English translation

ざあ　と梢の窓が開いて、

じき、サアカスがはじまるのかとわくわくした。

*Whoosh* The treetop window is opened.
It’s time. Is the “show” about to start? I’m trembling with excitement.

This feels a little bit weirdly worded and I think it’s because I’m not grasping something from the Japanese.

Any help would be appreciated!