Glad this topic bounced back up cause I missed it..
Imo - it's based on who you are. Meaning, which are you first - a writer or a producer? For instance, I also do both but at heart, I'm a lyricist. That means, I'm writing even when I wasn't thinking about writing (washing dishes, mowing the lawn, watching tv, etc... lol).. The way I do it is, I write a verse or a song independent of the beat. I could have written the verse/song to the Jay-Z 4:44 beat but, not have a beat of my own created yet. Then, at some point, I produce. But, I'm not producing with the intent of matching it to the verse/song I created, I'm producing just cause its time to produce - knowing that most likely, the end product wont go with the verse/song I created. Then I repeat the process.
I agree with Blitz that it's tough to balance when you got fam/work, etc but, you find the time. Find a system that works. If you're like me, and you write, well you should be writing all the time based on inspiration and vibe - and depending on how strong either of those are on any given day, you can either come out with 1 or 2 verses or a song and the chorus too! For me, Producing in most cases, is part of a system I created - or time I set aside each week to get at it. There are those rare cases when I wake up with a beat or melody in my head and I need to jump on the DAW but, for the most part, it's finding a slot of time each week to knock something out.
Once I have a beat that's knocking, I go back to my rhymes and see what feels like it's supposed to go with that beat. For instance, I have a song called: Finally Free. I created the beat for that song in 2006 but the rhymes just came to me 2mths ago and I finished the song for the EP I did this month. Yeah, it's a tough tough balance - but, when you love to do it - you absolutely find the time.
Wayz