When the noun, 以来（いらい） ‘ever since’ is paired with the て-form of verbs, or with nouns, it indicates that (B) is something that has continued non-stop since (A), or will continue non-stop from (A). This may be interpreted as ‘since (A)’, ‘henceforth’, or ‘ever since (A)’.
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2年（ねん）前（まえ）にタバコをやめて以来（いらい）、一本（いっぽん）も吸（す）ってない。
I haven’t smoked a single cigarette ever since I quit 2 years ago.
日本（にほん）に来（き）て以来（いらい）、全然（ぜんぜん）母国（ぼこく）の友達（ともだち）と連絡（れんらく）をとっていない。
I haven’t kept in touch with my friends back home ever since I moved to Japan.
久（ひさ）しぶり！卒業（そつぎょう）以来（いらい）じゃない？
Long time no see! (We haven’t met) since graduation, right?
入社（にゅうしゃ）以来（いらい）、あの先輩（せんぱい）には色々（いろいろ）とお世話（せわ）になっている。
That senpai has helped me in many ways since I’ve joined the company.
The key point of
以来（いらい） is that it indicates an ongoing state. Due to this, it focuses on (B) being something that will continue non-stop until a change is caused externally.
Caution - Occasionally,
以来（いらい） may also be used to express a specific number of (B) that has occurred since (A). While this use is closer to ‘since’, it still just indicates that ‘in total’, (B) has occurred ‘ever since (A)’. This will place a stronger emphasis on the amount of (B) being shocking in some way than a simpler structure like から.
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海外（かいがい）転職（てんしょく）して以来（いらい）、5年（ねん）も日本（にほん）に帰（かえ）っていない。
I have not been back to Japan for five years since I changed jobs overseas.
去年（きょねん）この大学（だいがく）に入学（にゅうがく）して以来（いらい）、１回（かい）しか実家（じっか）に帰（かえ）っていない。
I have only been back to my parents' house once since I entered this university last year.