Should I wait to read onyx storm?

I’ve recently read fourth wing and iron flame (read them so fast I was obsessed). I didn’t realize the series wasn’t done till after iron flame, with that I’m worried a cliff hanger on onyx storm might be annoying if I can’t read the next book anytime soon. I’m okay with the ending for iron flame for now but am also excited to read onyx storm. I’m wondering should I wait till the fourth book is out to read it?