Hi Elly! a couple of thoughts - re: dressing an hourglass....i find that softer, thinner, stretchier, drapier fabrics are much more 'forgiving' when it comes to 'extra bulk' around the waist. With these types of fabrics you don't have to take in as much as you would a stiffer, thicker, more stable fabric if you are tailoring at the waist, for example. I've found this to be the case for stretch wovens as well as knits (so you can get that more tailored look you like).
re: clothes for a new job. Every manager i've known (worked with or for, or to whom i'm related) understands that a person takes a while to 'get dressed' nicely for a new position. They also understand this will take even longer if you are new to the field or haven't worked for a while. The important thing is for you to show you are making an effort to be appropriately clothed for your position.
As Aida points out, you may have to wear less than perfect items until you can get a hold of the items you really want. In my experience most managers will notice that you are not dressing according to the dress code while they will not care that your hem is at a dowdy length, you are wearing a less than flattering color, blouse is kind of baggy at the waist, etc.
Depending on the state of your closet, budget, and shopping options one approach would be to buy some 'stopgap' work appropriate pieces at cheap prices (sales, T.J.Maxx, etc.). You can wear these at work while you acquire what you really want. It's not ideal, but then dressing for work often isn't : )
HTH!! happy afternoon, steph