Stupidity=partial request

I would send the partial, and then start writing very fast. But you have a 100 per cent request rate so far! Congratulations and welcome.

Some might not agree with my advice, but this was what I did when I was in almost EXACTLY the same situation. I finished the MS in three days and sent it off.

Now you are lucky, you have the partial request which will probably take several weeks so you have time. I was asked for my FULL the DAY AFTER I sent out my query. I had my parents go over the grammar of the rest of the MS and I finished 30 000 words in three days, made them as polished as possible and got it to them.

So if your first 50 pages are good, send those off. And then get working! Make the rest of your MS awesome, throw out your back if you have to sitting at your desk writing away, but get it done!

Burn the midnight oil. You don't get chances like this every day.

And I am going to say just the opposite. I would wait until you feel it's finished BEFORE you send the partial- Agents are busy and don't necessarily have a time line- think of how most of them don't get to reading it for 3 months- I would polish the first 50-100 pages and finish the ending before sending...
JMHO

Here's the thing, you are going to get a lot of advice here, some of it opposing. ORION of course makes an excellent point, but I would also be wary of waiting too long on sending a partial.

The reason we can't tell you exactly what to do is we know nothing of your writing abilities, nor the state of your MS.

In my situation, I tend to write first drafts as if they are third or fourth drafts. My editing is much more fine tuning than huge structural changes. I can also, when i put my mind to it, work very quickly and carefully at the same time. I was able to complete the MS in three days and know that it was in very good shape. It wasn't a rough draft by any stretch of the imagination. In fact, to be honest, I think those last pages were some of my best in that novel (which still is a bit weird to me).

At any rate, it comes down to you. Do you feel capable of finishing the MS quickly and well? Do you feel the first 50 pages are solid and are unlikely to change when you get to the end of the MS? These are really tricky questions, and you have to answer them honestly. If you don't feel ready, then you should definitely take ORION's advice. Ask the agent if they mind waiting a few weeks. Chances are that will kind of annoy them, because it will show you jumped the gun which is rather unprofessional, but it might not make them say no either.

Jellycat, I'm glad to hear you made the decision to move forward. Good luck!