During Golden Week an old friend came to visit me in Japan, with his girlfriend. I was very happy to see him, and we had a lot of fun together. I gave them a tour of Osaka by bicycle, and we went to Kobe and Nara too. We ate lots of tasty food every day and went to lots of fun bars and pubs at night. It was really fun, but it was also much more tiring and expensive than I expected (more+adjective+than I expected). I still really want to see my friends, but I hope they don’t all come at once!
‘At once’ has two meanings:
1) Right away, immediately; For example – ‘When the bell rang he left at once’
2) At the same time. For example – ‘The DJ played three songs at once. He was fired.’