Sorry to hear that you're going through this 
DS started chemo at 6 months old (6 cycles over about 4 months). He had most of his chemo as a day patient, with only one overnight stay, so is it certain that you'll actually be staying overnight in hospital?
It was quite a long time ago for us - and we had a great outcome in the end! - but a few random things that come to mind are:
I was surprised by how long each infusion took (about 4 hours, from memory!) so be prepared for a lot of boring waiting around while tethered to a drip stand. Make sure you come armed with plenty of things to amuse your DC during that time, especially as it can be difficult to actually go anywhere once the chemo has started.
One of the chemo agents used for DS caused both explosive diarrhoea and a spike in temperature, so be prepared for reactions like that!
Eating was a massive thing for us, especially as DS started chemo at the same time as we were starting to wean him. He carried on breastfeeding throughout, but lost his appetite for pretty much everything else apart from the odd bit of fruit. We had support from a dietician throughout, so see if that's an option for you. In the end, he was NG-fed for most of the chemo period (they trained us to do this at home), which took the pressure off us to get enough calories in him, and meant that we could concentrate on keeping mealtimes about fund and exploration. His appetite didn't recover fully for a few months after chemo finished, so it had a massive effect on his weaning overall.
We spent the whole 4 months being hyper-vigilant about infections, especially an infection in his Hickman line which could have been really dangerous. We monitored his temperature several times a day and we're under strict instructions to go straight to the hospital if it ever reached 38°C, even if it was the middle of the night. He did end up being admitted because of this a couple of times, and they gave him broad-spectrum antibiotics until they'd figured out what was causing the fever.
It took quite a while for his hair to fall out, so he spent the first two months of chemo with cute, fluffy, tufty hair, like a chick! When it did eventually fall out, I did have a moment of thinking "oh god, now he really does look like a child with cancer", but we got used to it pretty quickly. And it's much easier at that age because you kind of expect babies to be bald, unlike, say, 6 year olds 
.
One last thing: babies re incredibly fidgety and wriggly, so it can be very difficult to keep them still during infusions, or stop them fiddling with tubes and dressings. We had a cotton "wiggly bag" to keep the end of his Hickman line in, but it was still a daily challenge to keep it clean and stop him from playing with it. Vests were really useful for containing everything out of his reach! He also became expert at hooking a finger under his NG tube and pulling it out 🙄