We brought a nine week old terrier pup home in October. I had two weeks off to settle her in while OH got ahead with work. He mostly WFH and I work a few minutes walk from home. I have semi flexible hours.
It was tough to begin with. He didn't get much work done so caught up when I got home. I used to come home for an hour at lunch to give him a break. Luckily both employers were very supportive of puppy disruption and care arrangements when he had to go into the office for odd meetings and I often work extra unpaid so I was able to take a lot of TOIL.
At 5 months it got much better. At 8 months it's fairly easy most of the time but there are the odd moments!
Toilet training is just the half of it really. It's keeping them out of everything. Our pup has never destroyed anything she shouldn't or chewed as we were on her all the time. One of us 24/7 so no bad habits could be established. Biting. So much biting. From sleeping puppy to shark puppy. You have to drop everything and play. Training - we focused on rewarding the good stuff but she also goes to a training class once a week (I help run a dog training club).
To begin with pup had to be on a lap. All the time. So he would work with her sitting on him. Laying up him some days. She frequently featured in team briefs! She gradually got more confident so we gave her a bed on the floor by his feet. Now she sleeps wherever she likes, often in another room. We didn't force anything just let her grow up naturally.
Obviously lots of people don't do this. But you have one chance to raise a happy, confident, well adjusted puppy who will hopefully grow into a confident, happy, well adjusted buddy.
You really can't leave them at all in the early days. Cocker spaniels are very people orientated dogs so do need extra support learning to be ok on their own. So you need to factor that in for quite a few weeks/months yet.
It's tough but it's worth it. Initially we said 'never again' but as we are seeing the lovely dog she is growing into it's become a 'maybe if we can't rescue'.