Hey Adam, this is very bad practice, and will cause you so much extra work once you get into actually putting the song together in regards to mixing music, your song’s arrangement, and getting things to line up.

If you choose to record without any audio, you at least should be recording over a metronome at the tempo of the song.  If you don’t record vocals at the song’s tempo, your timing will not line up, and you’ll have to do LOTS of cutting of the vocals, rather than just slight nudging here and there.

To hear your whole song while recording vocals in FL Studio, you just need to hit record, arm a mixer insert, then hit play in SONG MODE.

If any of that confuses you, let me know!