Hi Jill!
During the summer months, Chip 'n' Dales Campfire Sing-a-long is generally held at 8.00 pm at
Disney's Fort Wilderness Resort (7.00 pm during the autumn and winter). You can always ask the front desk at your resort to confirm these times. You can take a boat from Disney's Wilderness Lodge to Fort Wilderness, but I would recommend allowing at least 60 minutes for the whole journey, so that you can arrive in comfortable time for the Campfire.
I would suggest a dining reservation at
Whispering Canyon Cafe of around 5.30/5.45 pm so that you have enough time to enjoy your dinner, and all the entertainment here.
If you are spending the whole day Disney's Hollywood Studios, you can take a bus from there directly to Wilderness Lodge. Otherwise, you can take a bus from Disney's Port Orleans Resort, but you would have to change buses at Downtown Disney.
Please let me know if you have any further questions!