When Peter Parker was bitten by the spider he immediately became Spiderman.
The entire movie is Peter learning how to utilize the 'powers' he ALREADY had. Although he was fully Spiderman he still had to 'practice' shooting webs and climbing walls until he became proficient in walking out (or swinging out) who he ALREADY WAS.
He was NOT bitten, then had to TRY TO BECOME Spiderman; he WAS already Spiderman as soon as he was bitten.
That is the same with us as Christians. When we accept Jesus into our hearts, we are immediately made righteous, holy and complete in Christ (Colossians 2:10). We must now 'practice' using the wisdom, knowledge and truth from the Word to walk out who we ALREADY ARE.