Is it permissible to fast the six days of Shawwal before making up for the days one missed in Ramadan if there isn't enough time to fast both?

Fasting six days of Shawwal is linked to completing the Ramadan fast, and its reward is not attained unless the Ramadan fast is completed, both in performance and in making up missed days, as the Prophet, peace and blessings be upon him, said: "Whoever fasts Ramadan, then follows it with six days from Shawwal, it will be as if he fasted the entire year."

So, if a Muslim has missed fasts from Ramadan to make up, it is obligatory for them to make them up before fasting the six days of Shawwal. However, if someone has a legitimate excuse, like a woman in postpartum bleeding (nifas), and making up the Ramadan fasts takes up the entire month of Shawwal, then it is permissible for her to fast the six days in Dhul-Qa'dah, and she will receive the reward of one who fasted them in Shawwal, because the delay here is due to necessity. But whoever does not fast them without an excuse until Shawwal ends, will not receive this reward.