Give the swan a little more time. Incubation usually lasts 35-45 days. The incubation does not start until the last egg has been hatched, so your timeline may not be the same as the swan's.

Also, if you disturb the eggs at this time, she may abandon the whole nest and try to re-clutch (lay more eggs) which may be detrimental to her health.

Egg candling is usually the way to check and done at a very early time in the incubation process. The Regal Swan