When I come (ερχομενος). Present middle participle of ερχομα with the time of the future middle indicative ελευσομα (coming I shall come).

In the fulness of the blessing of Christ (εν πληρωματ ευλογιας Χριστου). On πληρωματ, see Romans 11:12. Paul had already (Romans 1:11) said that he had a χαρισμα πνευματικον (spiritual blessing) for Rome. He did bring that to them.