The reward and significance of tilāwah of the Qur'ān during Ramadhān is indeed great. Realising this, someone who is currently reading three juz per day may entertain the noble intention of reading six juz a day – not from tomorrow, but next Ramadhān! It would be no sin if he were to start reading six juz instead of three this very Ramadhān!
It is also noticed that before the advent of Ramadhān, many people realise that indeed they should engage in tilāwah during the blessed month. However, with this noble thought in mind, they fail to do any tilāwah during the remaining days of Sha'ban and wait for the first of Ramadhān to begin. Just imagine how much reward they deprive themselves of!