Here in the printer’s manuscript, Oliver Cowdery made a correction in the word order; he initially wrote “I pray for them continually by day”; then shortly afterwards he crossed out for them and supralinearly inserted it after continually (the level of ink flow is unchanged). Either word order is possible, so Oliver was probably correcting to 𝓞 rather than editing the text.
Other examples in the text show that the word continually can come before or after the verb pray, although most come after the verb:
Note that in two of the above cases (2 Nephi 9:52 and Alma 62:51), continually comes after a prepositional phrase, which is the same word order that Oliver Cowdery initially wrote in 2 Nephi 33:3 (“I pray for them continually by day”). But two examples are not enough to show that the corrected word order in 2 Nephi 33:3 is somehow in error.
Summary: Maintain in 2 Nephi 33:3 the corrected word order in 𝓟: “I pray continually for them by day”.