Growing up as a musician is all about maximizing the gear you've already got. Learning to squeeze every bit of capability out of your gear doesn't happen if you buy ahead of demand. Rather than anticipating a problem, you have to at least rehearse with the band a bit to see how it sounds.
In my past I recall having to step up to the next level of gear once or twice. The determining factor wasn't purely about volume, it was about tone. Most any practice amp sounds just fine in a bedroom at low volume. However, underpowered gear can be very challenging in terms of finding a good tone at loud volumes. Trust your instructor to let you know if it is loud enough. Trust your ears to tell you if it still sounds good at volume.
When I'm early on in a long pursuit, I like to give myself milestones and achievements to shoot for. Perhaps a new bass amp sometime down the road is a reward for completing a year of band and good grades, or maybe placing well at competition. Delayed gratification. Motivation. Setting goals. Making do with what you've got. All great skills to add to your musical talents.
As a side bonus, if you decide to get an amp and give yourself months instead of days leading up to the decision, you will invariably make a better choice by doing more research, testing more amps out for yourself, and avoiding an impulse purchase.
I humbly (and totally) disagree. It's not creative, expressive nor is it a right-of-passage to play on junk when one should be working on learning and improving one's playing ability.
Start with a toy amp and one cannot get anything closely resembling quality and anything resembling capacity out of it. That's called 'headroom' and it's frustrating to be held back by the stigma of cheap and powerless.
If one buys big - as big as one can afford - then one has a piece of equipment that will hang in as one grows in ability and prowess. Of course, research a lot before one plunks down greenbacks - but don't buy with the idea that one will upgrade later on.
I came back to playing after a 47+ year hiatus and went to 600 Watts as first purchase. Why? Because it's capable --- more capable than I was then and possibly still now.
I see all sorts of requests for 'what should I buy now that my 15 Watt, 8-inch amp sux' posted here on TB when one finds one has outgrown one's (toy) amp'. That's a frustrating waste of money IMO.
Why cripple oneself with inferior gear in the first place?
Do one's basic research - decide what type of music one wants to play and buy according to the style: bright 'modern' gear for slapping and - dare I say it: 'metal'.
Buy mellower, old-school gear for that Motown and pre-Beatles sound.
Of course, gear can cross over in all sorts of musical styles (is it really in the fingers as some say?) and EQ'ing is the rage too - so there's that to consider.
Pedals (stomps) and accessories will also move one's sound/amp/bass to new avenues too.
In the end - a cheap tiny toy amp is still a cheap tiny toy amp - one that will need to be upgraded anyway, sooner than later. (Something about turd-polishing, I believe.)
