We have a 19 week old Working Cocker. We cage him at night in the kitchen, and he cried for an hour the first night, longer on the second, and after 4 hours of crying on the 3rd night i’d had enough, and went to him and just said “enough” firmly, didnt shout.
Now, i know you shouldn’t do that,(I had surgery in the morning and didnt want to see my patients when suffering from sleep deprivation) but ever since he’s been fine, no crying at all.
We both work full time, and go back to see walk and feed him at lunch. If we work away we take him to work, caged in the back of the van and walk him whenever we get a break, he’s been fine, no chewing, no anxiety, good as gold and completely mental when he’s with us just like Spaniels should.
Just stick with the routine, the pup will fit around what you need, as long as you give it all the attention and walks, fuss it requires it will be just fine!
I have always had terriers before and seperation anxiety and crying for attention always goes given enough time :D