Quidam is incorrect.
SamuraiY said:I don't think this is really covered in the books. Isn't that chart for creating new characters, or am I thinking of something else? I would say that this is up to your DM.
dcollins said:All the designers are in agreement that the "Level Advancement" ordering on PHB p. 145-146 is mandatory and not optional.
The first item on the list is "Choose Class". Hence, no other benefits (such as feats) are acquired in sequence to help satisfy class prerequisites. You'll have to wait another level for that.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.