If you change your nose piercing too soon and it's not healed enough yet the nose piercing could actually close up or you could tear the nose piercing and cause an infection or bleeding.
It's best to wait for at least 4 months before removing your first nose piercing and changing it out for another different one.
If you do want to change your nose piercing sooner then it would be best to have a nose piercing professional do the job.
That way you prevent infection and possibility of the nose piercing closing up.
Sometimes it may take some peoples nose piercing 6 months before it completely heals so if it hasn't healed up enough in 4 months then waiting 6 months before changing the nose piercing nose ring would be best.