That's good plan...only on paper. It would require too much red and green packs so that tactic isn't cost-effective. Besides that, for 12-15T you can sign young 3* player from academy, but for less tokens you can buy yound 5* player on auction which already has great quallity advantage over that 3*
Read existing threads on forum about young players, their growth and investment. Also keep in mind that bad form makes any player useless no matter how high quallity he has.