Usage of「次第に」with the past tense


I am confused as if I should put the verb preceding 「次第に」 at the past tense or
just use the dictionary version:

> ランチを食べた次第に帰った

Or

> ランチを食べる次第に帰った

Also, if this grammar is not appropriate in this case, could you please
additionally provide an example of other constructs that carry the following
meaning:

> Upon finishing lunch I went back home




It seems you have learned to use 「[次第]{しだい}」 incorrectly somewhere.

In saying "upon doing A", 「次第」 **cannot** follow directly the dictionary form
or the past tense form of a verb like [食]{た}べる and 食べた in your sentences. The
only verb form that can precede 「次第」 is the [連用形]{れんようけい}. For the verb 「食べる」,
the 連用形 is 「食べ」.

The tense of the sentence is NOT expressed with the verb preceding 「次第」. It is
expressed with the verb that follows 「次第」, which is the main verb of the
sentence. It is, of course, 「[帰]{かえ}った」 in your sentences.

The correct sentences are:

> 「ランチを食べ次第帰った。」 or
>
> 「ランチを食べ終わり次第帰った。」 （終わり is the 連用形 of 終わる）
>
> Both mean "I went home as soon as I finished lunch."

IMPORTANT: You do not add 「に」 to 「次第」 in these sentences. The only time you
need to is when you want to say " **gradually** ".

> 「[日本語]{にほんご}が次第 **に** わかってきた！」 = "I am beginning to understand Japanese!"




It seems you have learned to use 「[次第]{しだい}」 incorrectly somewhere.

In saying "upon doing A", 「次第」 **cannot** follow directly the dictionary form
or the past tense form of a verb like [食]{た}べる and 食べた in your sentences. The
only verb form that can precede 「次第」 is the [連用形]{れんようけい}. For the verb 「食べる」,
the 連用形 is 「食べ」.

The tense of the sentence is NOT expressed with the verb preceding 「次第」. It is
expressed with the verb that follows 「次第」, which is the main verb of the
sentence. It is, of course, 「[帰]{かえ}った」 in your sentences.

The correct sentences are:

> 「ランチを食べ次第帰った。」 or
>
> 「ランチを食べ終わり次第帰った。」 （終わり is the 連用形 of 終わる）
>
> Both mean "I went home as soon as I finished lunch."

IMPORTANT: You do not add 「に」 to 「次第」 in these sentences. The only time you
need to is when you want to say " **gradually** ".

> 「[日本語]{にほんご}が次第 **に** わかってきた！」 = "I am beginning to understand Japanese!"

