I'd do about 1/3 EI and change the water more often for now, and later..... every 2-4 weeks after the tank grows in nice and is well established.
EI is meant for CO2 enriched tanks. The idea is to start high and then taper off slowly till you see a deficiency and a lull in growth rates. Better than starting too low/no dosing and having poor growth, stunting and algae...........then hoping the plants will recover.
With Excel, it's about 1/4-1/3rd the growth rate of CO2 enriched tanks.
So you divide by 3 or 4 to get a dosage for EI.
Since the potential/possible build up over time is 3-4x less, you have a lot of wiggle room with regards to the water change % or frequency.
New tanks or algae issues: always do more water changes. 2-3x a week for 1-2 months. Add ferts after.