This is kind of a pet peeve of mine. If you are naming a note the accidental goes after the letter name. If you are naming an interval or scale degree the quality goes before the interval or scale degree. In general if you are unsure say it and it should make sense.
C#- C sharp
P5 - Perfect 5th
b3 - flat third
Now to the pet peeve. It is common in modern practice to write out scale degrees of scales as they relate to the major scale and your example does refer to the major scale. This is usually very useful when you are first learning different scales.
However that kind of defeats the point of scale degrees. Scale degrees are meant to be an enumeration of the notes of a scale not relating every scale to major. For example, in A natural minor the 3rd scale degree is C. In A major the 3rd scale degree is C#. If you asked "What note is the b3 scale degree in A major?" it would be C. If you asked "What note is the b3 scale degree in A minor?" it would be Cb because you are asking about A minor not A major. There are many times that someone will use a note outside of the scale/key that is when you are suppose to notate scale degrees with accidentals.
Both ways though are technically correct and you will see both. Basically if you see a lot of accidentals in scale degrees, someone is comparing the scale to major. If you see a scale that is not major and there are no accidentals then the scale degrees reference only the notes of scale and not comparing them to major.
A natural minor:
1 2 b3 4 5 b6 b7
Is equivalent to:
A natural minor:
1 2 3 4 5 6 7
I'm not going to lie the comparing the scale to major way is much more common, but it is good to know there is another way to notate it that you might come across.