Well I always Adlo before the tank pulls, and Stoneskin too if you have it (you should definitely get it if you don't). If it crits, you have a ton of mitigation before you actually have to heal.

First off, you should always be manually using Embrace. I'm using a controller, so I put Embrace on X and Physick on Square, so I just spam X (embrace), and when I need to actually heal I press Square and X at the same time. On the keyboard you can macro Embrace and Physick together if you have to, or just put Embrace on your hotbar, or put it somewhere easy and constantly click it. If you do this, often you won't even need to heal.

Adlo is sort of tricky to know exactly when to use it. You can't spam is, or you'll run out of MP. If you KNOW a bit hit is coming soon, Adlo right before. If the tank is taking super heavy damage where you're spamming Physick and Embrace and he's still dropping like a rock, use Adlo every few casts. If you're planning on DPSing, Swiftcast Stoneskin then cast Adlo to give as much protection as possible.

In general Scholars do MUCH better if you know exactly how the fight works. If you know there's unavoidable AoE damage coming, succor before. If there's BIG single target damage incoming, whether it is on the tank or a random target, either Adlo everybody just in case, or be quick and know you'll have to use it.

Another useful trick - if you want to DPS and you know the damage isn't super heavy, macro ALL of your DPS abilities. I consider this to be NON OPTIONAL for good scholars. The macro I THINK would be like this:

/micon "bio" Use whatever ability name obviously, this us just an example
/ac "bio" <t>
/ac "bio' <tt>
/pac "embrace" <t>
/pac "embrace" <f>

This make is so you can target who ever you want - tank or enemy - and be able to damage the enemy, and cure the tank. If you're targeting the tank, you'll DPS his target while using Embrace every time you use a DPS ability. If you're targeting a specific enemy - maybe helping kill an add really quickly that the tank isn't targeting - then you FOCUS target the tank and switch your target to the enemy. Eos will then cast Embrace on your focus target, the tank. Do this for EVERY ability - Ruin, Bio, Miasma, Etc.