When to start writing lyrics ? (How to finish songs)

[Ishi]

I've been practicing music production for near 5 years now.
My problem is, not being able to finish songs. I have only finished 1 song which i can call complete. which is great but not enough.
To clear things out, i can easily finish instrumental music, but not songs with lyrics.
I have tried different ways, but my problem is, i can finish music, i can finish lyrics. but i can not finish a song.
My question here is when do YOU start writing your lyrics for the music ?
Do you write lyrics before or after the music ? do you start midway somewhere ?
Do you start writing before the mix ? where exactly do YOU start ?

 

[OGBama]

I write without instrumentals but can write with one but the challenge is finding producers in the current era of music as the dilemma is oversaturation.