Is it a big problem to equalize early? Air you use for equalisation isn't wasted! When you equalize on 10m mark there is mask_internal_volume*2 liters of air in mask. I use it on my way back to surface - air under mask begin to expand and you can breath it again! There is sufficient amount of O2 and not too much CO2 there because it's about 10-20 seconds when you equalize first. My 2 cents: equalize when you want to- the air isn't wasted anyway.
[edit] Sorry. English is not my native language, as you may have noticed. By equalisation here i mean equalizing water pressure and pressure of air under mask, not in middle ear.[/edit]
