It is grammatically and semantically incorrect. First, you need to nominalize the verb with の. Second, you said "early," not "too early." "Too ADJECTIVE" is created as ADJECTIVE-root+すぎる.
Too early = 早すぎる
Too fast = 速すぎる
Too far = 遠すぎる
Too tall = 高すぎる
What you want is 諦めるのは早すぎる
“too early to”の検索結果（51 件）：英辞郎 on the WEB：スペースアルク