Is it worth investing now, or I'm late to the party?
if it would be that easy (just asking for it in a forum) everybody would be a millionair. never ask such a question anyone. Also you can get any possible answer and don't know what to do.
you can only know it if you do your own due diligence.
In fact IOTA (and crypto currencys in general) are a very high risk investement therefore nobody should invest in it without a good due diligence. IOTA potential is high but also the risk.
Regarding time you are too late because this coins ICO was about 2 years ago. This does not mean you are too late do make any profit. But the question is also what type of investor are you. usually early investor take more risk than late investors and therefore also the profit or loss is higher.