The simple fact of the matter is that there is no good time to write, because you can have a free day but not a single thought worth thinking, or you can have a busy day and the ideas are coming at you thick and fast. The truth is, you write when you can and even when you cant, even when you don't want to, you write. If you indulge that side of you that says I cant think of anything to say then you may not think of anything to say for days, weeks, months.
My best ideas usually come when I have absolutely no way of getting them onto paper, or I have just enough time to write key words - which i look at with confusion later on as it turns out I cant remember what the hell the key words refer to.
I indulged my writers block for too long, and it festered until I had to re-familiarized myself with my work all over again. Sometimes of course you need the break, you need to experience things that might trigger things for you later on, when it comes to writing, sometimes you need to let the ideas manifest and mature in your mind. So write something else, write a part of your story that will never make it to an audience, write a side story, write a scene that you think might be cute or exciting, but not necessarily move the plot forwards. It keeps you in the zone.
My goal for this month is to write 2000 words each week day - some days i might write more, but 2000 is my absolute minimum for my novel, because I have been too indulgent with myself. I have had so many ideas and now I have the flesh of the plot in my grasp, but not if i don't start to write it down,
So my advice to you is to just write, keep it fresh- even if its crap dont worry - you can edit it in the rewrite, if you can see its not supposed to be in the story you can cut it, If you haven't written anything you cant edit it and you cant cut it. Keep going keep going keep going - one of the worst things I used to do as a writer was to constantly go over and edit things that I had already written. If its a plot issue then put a note on it to change it later, If its bad writing dont worry too much. Just keep moving forwards and rack your word count up until you reach your target. once you have finished the book you can go back over it all and fix it, but if you don't get to the end there's no point in fixing the beginning.
Until next time