I don't usually do these sort of workings but does it totally matter if the moon is in Aries to free the soul of a binding ?

You can use most signs for it if the situation is dire. Preferred signs are:
Pisces (this is the best)
Scorpio
Capricorn
Aries
Taurus
Leo
Virgo
Saggitarius
Aquarius

All other signs should be avoided imo.

I just threw this together real quick. The lattermost signs are more neutral still, and only should be used if you need to start one ASAP.
Generally, Pisces, Scorpio, Capricorn should be your signs of choice if you want a permanent freeing of your soul from past dross. Aries can work too but it's possible that things relapse with this.

And most importantly, a freeing the soul working should always be started during a waning moon. Preferrably as close to the new moon as possible, but if you are in dire need you can start it during any of the above signs in a waning moon.