Is it more appropriate for someone who has been negligent in performing the night vigil (Qiyam al-Layl) and other acts of worship, and has both secret and public sins, and fears the consequences of becoming prominent in dawah (inviting to Islam) and the fame it might bring, to nonetheless seek Allah's help and take up the call to dawah, or is it more appropriate to delay and postpone this until Allah rectifies his condition, and to strive against his own self in that regard?

There is no contradiction between inviting people [to Allah] and striving to make oneself steadfast upon Allah's command. Abandoning da'wah (inviting to Islam) under the pretext of one's shortcomings is a whisper from Satan. It is not a condition for the da'i (caller to Islam) to be perfect or infallible; rather, he must strive against himself. Among the most important means of achieving steadfastness are: busying oneself with the Book of Allah through recitation and contemplation, reading books on softening the heart, accompanying righteous people, and frequently supplicating to Allah for steadfastness, knowledge, and righteous deeds.