I was in your shoes not too many years ago after I ETS from the Army. The only thing I had that resembled a suit was the Class A I had from the military.
Fortunately I had a mentor and was able to get up to speed and at one point exceed my colleagues in my professional appearance. Now I take pride in the way in which I dress and more importantly the manner in which I project my personal and professional appearance when dealing with members of my profession as well as people of influence.
See, in the military you had a ribbon rack to tell the story of your experience however, in the civilian world you have no such luxury. Therefore, you have to not only know what you need to know but also you have to have the look that speak for you when you are not talking. You can achieve this by taking care of your professional image.
Most likely those individuals that are CEOs and CFOs understand this and will expect you to understand the importance of your professional image as well as competency in your field.
Here are a few things I learned that may help you along the way:
1) Start from your shoes and work your way up. It makes no sense to have a well tailored suit with cheaply made shoes. Or shoes that look beat up.
Invest in a quality pair of men's dress shoes. There are countless threads on this site as to what shoe companies to look at. I will save you the trouble and give you a few:
Allen Edmonds, Alden, Peal & Co, Crockett and Jones, and the higher end of the shoe spectrum like John Lobb and Edward Green. Cap toe oxfords are you best bet when picking the style and IMHO black, cordovan, and dark brown are the colors I would recommend. Save the Walnut colored shoes for when you have more of the basics. Additionally, try to stay away from loafers when wearing a suit. I know some men like the look however, you are trying to look the part not set some kind of fashion statement at this point in your career.
2) Understand what your are actually buying, in way of fabric and construction of a suits. It does you no good to spend money on getting a suit tailored only to have it fall apart in three months.
3) Suit color is also important as well as the weight of the fabric. You stated you wanted a suit for warm weather. Be sure to let your sales rep know this but stay away from suits that are not 100% wool.
The colors you should start with should be Navy and charcoal grey. I know the Prince of Wales plaid might look great however, you do not want to be the guy that is known for wearing the same suit 3x times a week. ( I have one in my firm and we all feel real bad for the guy)
4) For your first few suits try and refrain from getting the fashion forward tight fitting suits I see a lot of the young executives wearing. You can have a well tailored suit that is not boxy looking without going the Black Fleece Tom Ford look. You will not win your colleagues trust by show how good your butt look by have trousers so tight that if you farted you split the seam and having a jacket so high that you can be mistaken for a woman from behind. Keep it simple keep it classic that way you are not bring a suit every 2 yrs when styles change and they will trust me.
5) Keep your ties simple but elegant. The cat and fish screen print tie might be tempting but, it can appear that you do not take your professional position or image seriously so why should others? Rep ties, dot ties and solids should be first and maybe a few paisley print.
6) Your shirts should fit in the body as well as in the arms as well. You do not want pillows nor do you want a shirt so tight that the button start to the pull or that you blow out the elbows. Also make sure you understand the difference between non iron and wrinkle resistant as there is a big difference.
7) If you are a big guy invest in braces ( suspenders) as they will be more comfortable and they keep your trousers on the correct waistline. However, if you are slim you could still wear them.
8) Get acquainted with what colors work best for you. Just because John in accounting looked great in. French blue shirt with a yellow tie does not mean you will too! Learn the color wheel and where you fit and work to maximize your visual impact.
I was fortunate to have and BB near me and the sales rep has been there for over 30 yrs. So I was able to get up to speed fast. However, you might not have one so, you will have to search for a brand that fits your style and budget. Best of luck and congratulations on your new position!