Some people find it easier to feel metta for themselves through re-experiencing the loving connection that they have with a friend. So, yes, it’s fine to start with Stage 2 of the meditation practice and then to go on to wish yourself well.
Sometimes it’s easier to experience our emotions in relation to others. I’m sure you’ve had the experience at some point of only realizing how strongly you felt about something when you found your voice catching as you talked to someone.
When we’re in relation with others often we paradoxically become more aware of ourselves. Humans are essentially social animals, and we’re simply not complete while in isolation.
With practice, though, I think you’ll find that it gets easier to cultivate metta for yourself. Just as in the friend stage of the meditation practice we are tapping into an already existing source of metta (or friendship) we can get to the point where our self-metta is so well developed that we can experience appreciation for ourselves as soon as we call ourselves to mind.
Apart from this variation, though, I strongly suggest that you stick to the stages of the meditation as they are outlined here until you have a strong body of experience with the practice.
However, once you’ve been doing the practice for a while (several months), I think it’s fine to begin experimenting with the structure of the practice to see what works for you.