My son is almost 4 and I have been back at work full time since he was 10 months old. I am a teacher so I work 5 days and it is a demanding job.
The first couple of months were hard trying to get into the routine and the inevitable bouts of illness when the start nursery. However, once we got into it, it's been fine.
DS absolutely loves his nursery, has some really close friends there and does so many different activities - the things they do with them amaze me!
It's also been good for me - I have continued my career, developed my skills and got a promotion since I returned which had I had a break/been part time would have been less likely to happen (might not be the case everywhere though).
In addition, my husband was unfortunately made redundant last year and my full time salary has been vital to us. Clearly this won't happen to everyone (and I hope it doesn't) but worth considering.
I find being organised is the key thing - usual things like making sure bags are packed at night, dealing with paperwork as soon as you get it and keeping a diary for all commitments (I use my phone which is also linked to my work calendar).
I would say, give it a good go for 6 months and if it really isn't working then, re-evaluate.
Good luck!