一...就... vs. 了...就?

Question

I have been revising HSK 3 grammar, and came across these two alternatives: - 我妈妈一起床，就做早饭 - 我妈妈起了床，就做早饭 On the basis that my book says that they both mean 'My mum makes breakfast as soon as she wakes up', is there any inherent difference between the two?

Answer 1

There is no difference between the two sentences, but 妈妈一起床 就做早饭 is s better Chinese sentence.

Answer 2

I do not think there is any difference.