That question comes down to two main factors:
1 Earning potential aka PRO "have it now pay later"
So if you can have the phone/laptop/whatever now and pay it later, that means you'll have money 6/12/18 months longer than you'd have it if you would pay it right now. So your money can potentially earn you interest in that time and that very much depends on the interest rate situation. If you get like 2% on your 1000 Bucks your paying for your phone or laptop you'll get 20 bucks of the purchase price if you do it that way. Another aspect is that your laptop may be your working instrument and will enable you to do work you otherwise couldn't do. In that case the laptop is an investment into your future earning potential.
2 Future Discount aka CONTRA "have it now pay later"
You know that Simpsons scene where homer downs a bottle of vodka mixed with a entire jar of mayonnaise and says :"That's a problem for future homer. Man I sure don't want to be that guy!"
Yeah.. that's what paying later means. Paying in the future will make your price sensitivity decrease because "It's a problem for future me". That means you are much more likely to over spend. By the way that is also the reason why stores offer financing options like this. You think it is interest rate free, which is true. But the price you are willing to pay if you not need to pay until in a year drastically increases. Therefor if you buy stuff for fun and not with the intention to generate money with it, pay it now. If you generate money with it, it's okay to pay later.