I think what is harmful about some kinds of early potty training is being forceful about it, having developmentally inappropriate expectations, or labeling a baby's potty behavior as good or bad when they are very young. In fact I think those practices are harmful at any age.
EC isn't about those things- it is just offering baby an opportunity to go in a potty instead of a diaper. It is gentle, patient, and about two-way communication with the parent in the lead on helping baby get to the potty when they need to go.
So I say go for it! Other common times to offer the potty is upon waking or at diaper changes.
I'd recommend The Diaper Free Baby or the EC Simplified e-book (very compehensive!) for more tips. Both have sections on ecing part time and ecing with older babies. Good luck!