I think you should put them up no matter how many 
you have. I enjoy looking at galleries no matter 
what the size. Its also fun to see galleries grow.

I had about 25 cels when I put up my gallery in 
November. I would have put it up a lot sooner but 
I am incompetent when it comes to the computer 
and I had a lot of problems. (It took about 1 
month and a lot of advice to get it to even 
upload properly onto geocities.) 

I update fairly regularly. At least once a month, 
if not more. I usually don't announce it though. 
(The site is slow to upload for many people and I 
don't have the skill to figure out how to speed 
it up.) There are currently about 70 cels now and 
three more on the way.