If you use dev tools, for example in Chrome, you can see the number of requests and total transferred data under the "Network" tab. To accurately replicate the experience of your users, you should do this with an empty cache - "Incognito" or "Private" tabs can be a great way to do this in most browsers. It's also worth remembering that the experience when testing locally will be drastically different from that when the effects of latency and upstream bandwidth come into play.
Be extremely careful about assumptions regarding users if you want to maintain usability. "Good enough" is extremely contextual, it may be "good enough" for a user on a desktop, laptop or premium tablet on a solid DSL connection - but anything but on a Edge or 3G connection on a phone. Wherever possible assumptions should be backed up by analysis of user agent strings from server logs, or from analytics software such as Google Analytics. It's also worth remembering that you may have relatively few mobile or tablet requests, not because mobile or tablet users don't want to visit the website - or choose to visit using another device, but because it is difficult, slow or even impossible to use on their device of choice. This case study from an engineer at YouTube illustrates how customers were being completely excluded from the site.
In general the page should be as small as possible, and you may want to look at lazy loading in addition to optimisations, which will help initial rendering time - in fairness though your estimated size is not much larger than the internet archive average page weight of 1681kB as at January 15th this year. Don't forget that other resources can also use a lot of space - JavaScript makes up 274kB of that average - and it's not clear if you have factored that into your estimate. Aggressive use of caching will help return visitors and minimise the data transfer required in these circumstances.
I always try to consider if you can justify the page weight cost against functionality. What is the objective of visitors to your site? Does the added functionality or imagery help this sufficiently to justify the performance cost. Many performance orientated developers are now actively setting a page weight budget but this is harder for single page apps where you cannot be as granular with resources.
Net
tab ofFirebug
,Chrome developer tools
to see how many requests are being made, and the total size of the page. – Aubreir