In D01 level,the aim of Mr.Delcamp is to train students to all aspects of classical guitar learning playing,using both hands,fingers,damping,music sheet reading,proper tempo,Rhythm,melody produced correctly and consistently.
It is advisable to use right hand fingers correctly and follow it with the music sheet.This is also the main principle of Arpeggio guitar technique to use specific finger on specific string unless advised by music sheet to change or alter the finger pattern. Lets take this example.
1.Right hand thumb stays and strike strings sixth,5th and 4th base strings E,A,D).
2.Index finger stays on and play string 3(G).
3.Middle finger stay and position on 2nd string(B).
4.Ring finger stay and play string 1 (high e)
If we as D01 students develop this discipline and regime in our playing consistently,with conscious effort,it will help to play and strengthen our ability to to apply this form of arpeggio technique in all right hand finger combinations.
So answer to your query, try to build this desire and conscious effort to play alternately using right hand fingers as indicated in music sheet.Practice it slowly.Pull your finger out slowly further and strike the specific string.Next do the same with next finger.Some time it happens that brain and finger sequence slipped unintentionally.