No. You can't take the feats granted by your new level until you choose a class, and you need those to qualify for the class. More generally, the level you're taking can't satisfy the requirements for the new class you're taking.
Player's Handbook page 6 details the steps of character creation. The very first one is choosing both race and class, while choosing feats is one of the last steps. This structure is repeated at level-up (pp. 58–9), with step one being choosing your class for the level and step seven being choosing your feats. You can't do these in a different order, and the contents of one step can't qualify you for the same step (so you can't use a race's benefits to qualify for a class).
That means that, regardless of whether it is your 1st or 20th level, you must already qualify for a class before choosing it, since choosing it is step 1.
There is one way around this though: racial HD. If your character is of a race that starts with racial HD, they may already have feats due to the racial HD. (Since these function as existing levels, you already have all the benefits of these HD, including feat choices, when you choose your 1st class level.) With enough racial HD, you can choose feats that will let you qualify for the Forsaken PrC at “1st” level.
Failing that, there is always your 2nd class level!