Generally speaking, once a week wcs for discus in a planted tank are acceptable only if you're keeping adult discus of 5" or larger.
Young fish under 3" are quite difficult to raise successfully, unless you're growing them out in a bare-bottom tank, with large daily wcs and multiple daily feedings.
Fish that size generally do not do well in a planted environment, and will not only not attain a decent adult size, many will be stunted in their growth, due to a lack of quality water conditions, particularly if wcs are infrequent - i.e. less than several times a week.
Younger, smaller fish are of course much less expensive than near adult, or adult fish because of the time, care, effort and attention needed by young fish to be grown out properly and well.
In a planted tank with few water changes, water quality & conditions are far from ideal due to the build-up of debris from lack of proper tank cleansing and lack of large amounts of fresh water, which in turn affects small discus (with underdeveloped immune systems) from developing properly, and often creates ill health.
One can't emphasize this enough - it's false economy to risk the loss or deformity of less expensive small discus by keeping them in less than ideal conditions - better to get larger fish and have much better chances of them all surviving in good health.
Apologies if I seem to be sermonizing - I just want to see discus newbies avoid frustration, disappointment, and loss of fish.
This advice is given with over 25 years of discus-keeping - just so you know.
If I may suggest, perhaps it would help you to read my Beginner's Guide to Getting Started with Discus - a Sticky located here in the Angel Fish & discus section.
Best of luck to you.