The phrase "after a certain stage" is correct and usable in written English.
It can be used to indicate a point in a process or development where specific actions or changes occur.
Example: "The project will require additional funding after a certain stage of development."
Alternatives: "beyond a specific point" or "following a particular phase".
Coitus during menstruation or after a certain stage of pregnancy is generally taboo.
Hospices are generally associated with cancer, where after a certain stage life expectancy is short and fairly predictable.
However, it is easy to see that ((X,sigma)) is weak 0-σ-complete because every 0-σ-Cauchy sequence in X is constant after a certain stage.
Daoism and Confucianism, at least after a certain stage in the development of these schools, exemplify the way that a set of interests intertwine with beliefs about the world.
After a certain stage this happens.
The death of pollen grains was similar in the lines studied after a certain stage of food reserve accumulation.
In terms of a cost-cost balance, surgical department coordinators may feel warned, that the implementation of critical pathways presents an investment into quality, but - at least after already having achieved a certain stage of process quality - may not necessarily result in cost reduction, but can even end up in increased human resource investment.
Continuous light is not required for fruit body development; after the mycelium has reached a certain stage of maturity, only a brief exposure to light is necessary, and fruit bodies will form if even subsequently kept in the dark.
Virtanen provides a further note of caution: "We should be aware that [the fragments] are, after all, drafts: unfinished as music, and representing only a certain stage in planning a new composition".
The good news is that in your 50's, after the kids have moved out and you've reached a certain stage in your career, your friends will still be there (along with some new ones acquired over the years).
