Bobbin may run out
 

I am a complete newbie and know nothing. I have
Brother innov-is NQ1600E and the bobbin is less than half full.
My question is this, if the bobbin runs out in middle of design, I
think machine will stop. At that time, do I refill the bobbin, hit
something, maybe 'start' or something and machine will continue
like there was no interruption. Right?

I usually fill about 7 bobbins before I start to embroider. Don't know why I picked that number but I want to have the extra bobbin ready. I do not have your specific machine. If you have a manual, I would look in it to determine how the machine gets to where you left off. Some machines will are easier than others to reposition. You want it to start again a 6-7 stitches before you ran out of bobbin as far as I recall. Just took a glance, If you don't have a manual, you can download one.

Your machine will tell you your bobbin is about to run out. Stop the machine and put in a new bobbin, don't wait until it runs out. It's always a good idea to back it up a few stitches before starting the embroidery again. Look in your manual under "Embroidering" and it will give you the steps to backing up and repositioning your project. I wind an extra bobbin before I start, it's amazing how much stitching you can get out of one bobbin. Of course if you're stitching a big design you will need a few more.

Yes, check the manual. It will show you the sequence of changing a new bobbin.

For embroidery projects, I check the bobbin between thread-color changes if it's starting to run low. Most often, I change it before it runs out. I use the left over bobbin thread to do piecing. I also use pre-wound bobbins as there is more thread on them.

Before changing bobbins, I write down the step and the stitch count number so I can find my way back into the design if needed. Be careful that you don't bump or re-position the arm when removing the hoop for bobbin changes.

you have to keep the bobbin sensor super-clean for it to consistently work properly.
i don't take chances anymore.
if i have any doubt whether a bobbin will last through embroidery i put in a new one.
i use the partial bobbins while piecing or for test runs.

My machine will tell me when the bobbin is getting low because of the sensory device in the bobbin. Be sure to always use the correct bobbins so the sensory will work. My machine also backs up 5 stitches when I remove the bobbin to change it out. I add another extra 5 stitches for good measure. That last 5 stitches are my personal preference. As others have said refer to the manual.

I think the prewound bobbins are supposed to have a lot more thread on them than home wound bobbins. If it is that dense of a design, I would start with a full bobbin, though.

I also prewind a few bobbins because it is more convenient to prewind a few bobbins before starting. If you are using your machine to do machine quilting, the thread will show on the back of the quilt and would be prone to thread breaking from use. So, you might want to change the the thread in the bobbin to match the color of the backing of your quilt. Since this is a new machine for you, I'd practice quilting/embroidering on some test fabric for the project you are stitching, or on a practice quilt sandwitch. If the shop you bought it from has classes, it'd be a good idea to sign up for one.