When did Yongqi discover that she likes swallows?

I can't remember the specific episodes, but it must be the first few episodes. Swallows just entered the palace not long ago. I remember something like this: Yongqi and Ertai like the new swallow in Xingege very much, think she is very unusual and always play with her. Ertai also expressed his love for swallows. Yongqi once said (I forgot what happened), "I'm worried." (The swallow didn't hear this sentence clearly, and neither did he understand it. It is from this sentence that I clearly saw for the first time that he likes swallows. Er Tai also had a foil and told Er Kang Wei Zi that if the swallow saw Yong Qi didn't blush, I would have chased her. It can be seen that Yongqi also likes swallows.